The Challenger Deep is the deepest-known point of the
seabed
The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'.
The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...
of
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, with a depth of by direct measurement from deep-diving
submersible
A submersible is a small watercraft designed to operate underwater. The term "submersible" is often used to differentiate from other underwater vessels known as submarines, in that a submarine is a fully self-sufficient craft, capable of ind ...
s,
remotely operated underwater vehicle
A remotely operated underwater vehicle (technically ROUV or just ROV) is a tethered underwater mobile device, commonly called ''underwater robot''.
Definition
This meaning is different from remote control vehicles operating on land or in the ai ...
s and
benthic lander
Benthic landers are observational platforms that sit on the seabed or benthic zone to record physical, chemical or biological activity. The landers are autonomous and have deployment durations from a few days (for biological studies) to several ...
s, and (sometimes) slightly more by
sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect o ...
bathymetry
Bathymetry (; ) is the study of underwater depth of ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water de ...
.
The Challenger Deep is located in the western
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
, at the southern end of the
Mariana Trench
The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maximum know ...
, near the
Mariana Islands
The Mariana Islands (; also the Marianas; in Chamorro: ''Manislan Mariånas'') are a crescent-shaped archipelago comprising the summits of fifteen longitudinally oriented, mostly dormant volcanic mountains in the northwestern Pacific Ocean, betw ...
. According to the August 2011 version of the
GEBCO
The General Bathymetric Chart of the Oceans (GEBCO) is a publicly available bathymetric chart of the world's oceans. The project was conceived with the aim of preparing a global series of charts showing the general shape of the seafloor. Over the ...
Gazetteer of Undersea Feature Names, the Challenger Deep is deep at .
This location is in the ocean territory of the
Federated States of Micronesia
The Federated States of Micronesia (; abbreviated FSM) is an island country in Oceania. It consists of four states from west to east, Yap, Chuuk, Pohnpei and Kosraethat are spread across the western Pacific. Together, the states comprise a ...
.
The depression is named after the British
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
survey ship , whose expedition of 1872–1876 made the first recordings of its depth. The high water pressure at this depth makes designing and operating exploratory craft difficult. The first descent by any vehicle was by
Jacques Piccard
Jacques Piccard (28 July 19221 November 2008) was a Swiss oceanographer and engineer, known for having developed underwater submarines for studying ocean currents. In the Challenger Deep, he and Lt. Don Walsh of the United States Navy were the ...
and
Don Walsh
Don Walsh (born November 2, 1931) is an American oceanographer, explorer and marine policy specialist. He and Jacques Piccard were aboard the bathyscaphe ''Trieste'' when it made a record maximum descent into the Challenger Deep on January 2 ...
in the manned
bathyscaphe
A bathyscaphe ( or ) is a free-diving self-propelled deep-sea submersible, consisting of a crew cabin similar to a bathysphere, but suspended below a float rather than from a surface cable, as in the classic bathysphere design.
The float is fi ...
''
Trieste
Trieste ( , ; sl, Trst ; german: Triest ) is a city and seaport in northeastern Italy. It is the capital city, and largest city, of the autonomous region of Friuli Venezia Giulia, one of two autonomous regions which are not subdivided into provi ...
'' in January 1960; unmanned visits followed in 1996, 1998 and 2009. In March 2012 a manned solo descent was made by film director
James Cameron
James Francis Cameron (born August 16, 1954) is a Canadian filmmaker. A major figure in the post-New Hollywood era, he is considered one of the industry's most innovative filmmakers, regularly pushing the boundaries of cinematic capability w ...
in the deep-submergence vehicle ''
Deepsea Challenger
''Deepsea Challenger'' (DCV 1) is a deep-diving submersible designed to reach the bottom of Challenger Deep, the deepest-known point on Earth. On 26 March 2012, Canadian film director James Cameron piloted the craft to accomplish this goal i ...
''. Between 28 April and 4 May 2019, the DSV Limiting Factor completed four manned dives to the bottom of Challenger Deep. Between 6 June and 26 June 2020, the DSV ''Limiting Factor'' added six completed dives during the first Ring of Fire Expedition. The deep-sea submersible ''Fendouzhe'' (奋斗者, ''Striver'') completed a crewed dive to the bottom of the Challenger Deep on 10 November 2020 with three scientists onboard whilst livestreaming the descent. Between 1 March and 13 April 2021, the DSV ''Limiting Factor's'' second Ring of Fire Expedition added five completed dives. During the third Ring of Fire Expedition in the summer of 2022, the DSV ''Limiting Factor'' made an additional nine descents to the Challenger Deep. As of July 2022 the
list of people who descended to Challenger Deep
The Challenger Deep (CD) is the deepest known point in the Earth's seabed hydrosphere, a slot-shaped valley in the floor of Mariana Trench, with depths exceeding 10,900 meters. It is located in the Federated States of Micronesia. In 2019, sonar ma ...
includes twenty-seven people.
Topography
The Challenger Deep is a relatively small slot-shaped depression in the bottom of a considerably larger crescent-shaped
oceanic trench
Oceanic trenches are prominent long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic tren ...
, which itself is an unusually deep feature in the ocean floor. The Challenger Deep consists of three basins, each long, wide, and over in depth, oriented in echelon from west to east, separated by mounds between the basins higher. The three basins feature extends about west to east if measured at the
isobath
Bathymetry (; ) is the study of underwater depth of ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water de ...
. Both the western and eastern basins have recorded depths (by sonar bathymetry) in excess of , while the center basin is slightly shallower. The closest land to the Challenger Deep is
Fais Island
Fais Island is a raised coral island in the eastern Caroline Islands in the Pacific Ocean, and forms a legislative district in Yap State in the Federated States of Micronesia. Fais Island is located approximately east of Ulithi and northeast o ...
(one of the outer islands of
Yap
Yap ( yap, Waqaab) traditionally refers to an island group located in the Caroline Islands of the western Pacific Ocean, a part of Yap State. The name "Yap" in recent years has come to also refer to the state within the Federated States of Micr ...
), southwest, and
Guam
Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
, to the northeast.
Detailed sonar mapping of the western, center and eastern basins in June 2020 by the DSSV ''Pressure Drop'' combined with crewed descents revealed that they undulate with slopes and piles of rocks above a bed of pelagic ooze. This conforms with the description of Challenger Deep as consisting of an elongated seabed section with distinct sub-basins or sediment-filled pools.
Surveys and bathymetry
Over many years, the search for, and investigation of, the location of the maximum depth of the world's oceans has involved many different vessels, and continues into the twenty-first century.
The accuracy of determining geographical location, and the beamwidth of (multibeam) echosounder systems, limits the horizontal and vertical bathymetric
sensor resolution
A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon.
In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...
hydrographers can obtain from onsite data. This is especially important when sounding in deep water, as the resulting footprint of an acoustic pulse gets large once it reaches a distant sea floor. Further, sonar operation is affected by variations in
sound speed
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At , the speed of sound in air is about , or one kilometre in or one mile in . It depends strongly on temperature as wel ...
, particularly in the vertical plane. The speed is determined by the water's
bulk modulus
The bulk modulus (K or B) of a substance is a measure of how resistant to compression the substance is. It is defined as the ratio of the infinitesimal pressure increase to the resulting ''relative'' decrease of the volume.
Other moduli describ ...
,
mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...
, and
density
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...
. The bulk modulus is affected by temperature,
pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
, and dissolved impurities (usually
salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
).
1875 – HMS ''Challenger''
In 1875, during her transit from the
Admiralty Islands
The Admiralty Islands are an archipelago group of 18 islands in the Bismarck Archipelago, to the north of New Guinea in the South Pacific Ocean. These are also sometimes called the Manus Islands, after the largest island.
These rainforest-co ...
in the
Bismarck Archipelago
The Bismarck Archipelago (, ) is a group of islands off the northeastern coast of New Guinea in the western Pacific Ocean and is part of the Islands Region of Papua New Guinea. Its area is about 50,000 square km.
History
The first inhabitants o ...
to
Yokohama
is the second-largest city in Japan by population and the most populous municipality of Japan. It is the capital city and the most populous city in Kanagawa Prefecture, with a 2020 population of 3.8 million. It lies on Tokyo Bay, south of To ...
Guam
Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
), but was set to the west by "baffling winds" preventing them from "visiting either the Carolines or the Ladrones." Their altered path took them over the undersea canyon which later became known as the Challenger Deep. Depth soundings were taken by Baillie-weighted marked rope, and geographical locations were determined by
celestial navigation
Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space (or on the surface of ...
(to an estimated accuracy of two nautical miles). One of their samples was taken within fifteen miles of the deepest spot in all of Earth's oceans. On 23 March 1875, at sample station number #225, HMS ''Challenger'' recorded the bottom at deep, (the deepest sounding of her three-plus-year eastward
circumnavigation
Circumnavigation is the complete navigation around an entire island, continent, or astronomical object, astronomical body (e.g. a planet or natural satellite, moon). This article focuses on the circumnavigation of Earth.
The first recorded circ ...
Sirena Deep
The Sirena Deep, originally named the HMRG Deep, was discovered in 1997 by a team of scientists from Hawaii. Its directly measured depth of is third only to the Challenger Deep and Horizon Deep, currently the deepest known directly measured ...
only 150 nautical miles east of the Challenger Deep), which would remain undiscovered for another 122 years.
1951 – SV HMS ''Challenger II''
Seventy-five years later, the 1,140-ton British survey vessel '' HMS Challenger II'', on her three-year westward
circumnavigation
Circumnavigation is the complete navigation around an entire island, continent, or astronomical object, astronomical body (e.g. a planet or natural satellite, moon). This article focuses on the circumnavigation of Earth.
The first recorded circ ...
of Earth, investigated the extreme depths southwest of Guam reported in 1875 by her predecessor, HMS ''Challenger''. On her southbound track from
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
to
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
(May–July 1951), ''Challenger II'' conducted a survey of the
Marianas Trench
The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maximum known ...
between Guam and
Ulithi
Ulithi ( yap, Wulthiy, , or ) is an atoll in the Caroline Islands of the western Pacific Ocean, about east of Yap.
Overview
Ulithi consists of 40 islets totaling , surrounding a lagoon about long and up to wide—at one of the largest i ...
atoll, using seismic-sized bomb-soundings and recorded a maximum depth of . The depth was beyond ''Challenger II''
echo sounder
Echo sounding or depth sounding is the use of sonar for ranging, normally to determine the depth of water (bathymetry). It involves transmitting acoustic waves into water and recording the time interval between emission and return of a pulse; ...
capability to verify, so they resorted to using a taut wire with "140 lbs of scrap iron", and documented a depth of .Ritchie, G. S., ''Challenger, the Life of a Survey Ship'', Abelard-Shuman (1958), p. 225
In New Zealand, the ''Challenger II'' team gained the assistance of the Royal New Zealand Dockyard, "who managed to boost the echo sounder to record at the greatest depths". They returned to the "Marianas Deep" (sic) in October 1951. Using their newly improved echo sounder, they ran survey lines at right angles to the axis of the trench and discovered "a considerable area of a depth greater than " – later identified as the Challenger Deep’s ''western'' basin. The greatest depth recorded was , at . Navigational accuracy of several hundred meters was attained by celestial navigation and LORAN-A. Note that the term "Challenger Deep" came into use after this 1951–52 ''Challenger'' circumnavigation, and commemorates both British ships of that name involved with the discovery of the deepest basin of the world’s oceans.
1957–1958 – RV ''Vityaz''
In August 1957, the 3,248-ton Vernadsky Institute of Geochemistry research vessel recorded a maximum depth of at in the western basin of the Challenger Deep during a brief transit of the area on Cruise #25. She returned in 1958, Cruise #27, to conduct a detailed single beam bathymetry survey involving over a dozen transects of the Deep, with extensive examination of the western basin and a quick peek into the eastern basin. Fisher records a total of three ''Vityaz'' sounding locations on Fig.2 "Trenches" (1963), one within yards of the 142°11.5' E location, and a third at , all with depth. The depths were considered
statistical outliers
Statistics (from German: ''Statistik'', "description of a state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industria ...
, and a depth greater than 11,000 m has never been proven. Taira reports that if ''Vityaz'' depth was corrected with the same methodology used by the Japanese RV ''Hakuho Maru'' expedition of December 1992, it would be presented as , as opposed to modern depths from multibeam echosounder systems greater than with the NOAA accepted maximum of in the western basin.
1959 – RV ''Stranger''
The first definitive verification of both depth and location of the Challenger Deep (western basin) was determined by Dr. R. L. Fisher from the Scripps Institution of Oceanography, aboard the 325-ton research vessel ''Stranger''. Using explosive soundings, they recorded at/near in July 1959. ''Stranger'' used celestial and
LORAN-C
Loran-C is a hyperbolic radio navigation system that allows a receiver to determine its position by listening to low frequency radio signals that are transmitted by fixed land-based radio beacons. Loran-C combined two different techniques to ...
for navigation. LORAN-C navigation provided geographical accuracy of or better. According to another source RV ''Stranger'' using bomb-sounding surveyed a maximum depth of at . Discrepancies between the geographical location (lat/long) of ''Stranger'' deepest depths and those from earlier expeditions (''Challenger II'' 1951; ''Vityaz'' 1957 and 1958) "are probably due to uncertainties in fixing the ships' positions".Fisher, "Trenches", ''The Earth Beneath the Sea'', p. 416, 1963 ''Stranger'' north-south zig-zag survey passed well to the east of the eastern basin southbound, and well to the west of the eastern basin northbound, thus failed to discover the eastern basin of the Challenger Deep. The maximum depth measured near longitude 142°30’E was , about 10 km west of the eastern basin’s deepest point. This was an important gap in information, as the eastern basin was later reported as deeper than the other two basins.
''Stranger'' crossed the center basin twice, measuring a maximum depth of in the vicinity of 142°22’E. At the western end of the central basin (approximately 142°18’E), they recorded a depth of .
The western basin received four
transects
A transect is a path along which one counts and records occurrences of the objects of study (e.g. plants).
There are several types of transect. Some are more effective than others.
It requires an observer to move along a fixed path and to count ...
by ''Stranger'', recording depths of toward the central basin, near where ''Trieste'' dove in 1960 (vicinity , and where ''Challenger II'', in 1950, recorded . At the far western end of the ''western'' basin (about 142°11’E), the ''Stranger'' recorded , some 6 km south of the location where ''Vityaz'' recorded in 1957–1958. Fisher stated: "differences in the ''Vitiaz'' icand ''Stranger''–''Challenger II'' depths can be attributed to the oundvelocity correction function used".
After investigating the Challenger Deep, ''Stranger'' proceeded to the
Philippine Trench
The Philippine Trench (also Philippine Deep, Mindanao Trench, and Mindanao Deep) is a submarine trench to the east of the Philippines. The trench is located in the Philippine sea of the western North Pacific Ocean and continues NNW-SSE. It has a ...
and transected the trench over twenty times in August 1959, finding a maximum depth of , and thus established that the Challenger Deep was about deeper than the Philippine Trench. The 1959 ''Stranger'' surveys of the Challenger Deep and of the Philippine Trench informed the U.S. Navy as to the appropriate site for ''Trieste'' record dive in 1960.
1962 – RV ''Spenser F. Baird''
The ''Proa Expedition, Leg 2'', returned Fisher to the Challenger Deep on 12–13 April 1962 aboard the Scripps research vessel ''Spencer F. Baird'' (formerly the steel-hulled US Army large tug ''LT-581'') and employed a Precision Depth Recorder (PDR) to verify the extreme depths previously reported. They recorded a maximum depth of (location not available). Additionally, at location "H-4" in the Challenger Deep, the expedition cast three taut-wire soundings: on 12 April, the first cast was to 5,078 fathoms (corrected for wire angle) at in the central basin (Up until 1965, US research vessels recorded soundings in fathoms). The second cast, also on 12 April, was to 5,000+ fathoms at in the central basin. On 13 April, the final cast recorded 5,297 fathoms (corrected for wire angle) at (the western basin). They were chased off by a hurricane after only two days on-site. Once again, Fisher entirely missed the eastern basin of the Challenger Deep, which later proved to contain the deepest depths.
1975–1980 – RV ''Thomas Washington''
The Scripps Institution of Oceanography deployed the 1,490-ton Navy-owned, civilian-crewed research vessel '' Thomas Washington'' (AGOR-10) to the Mariana Trench on several expeditions from 1975 to 1986. The first of these was the ''Eurydice Expedition, Leg 8'' which brought Fisher back to the Challenger Deep’s western basin from 28–31 March 1975. ''Thomas Washington'' established geodetic positioning by (
SATNAV
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pre ...
) with Autolog Gyro and EM Log. Bathymetrics were by a 12 kHz Precision Depth Recorder (PDR) with a single 60° beam. They mapped one, "possibly two", axial basins with a depth of . Five dredges were hauled 27–31 March, all into or slightly north of the deepest depths of the western basin. Fisher noted that this survey of the Challenger Deep (western basin) had "provided nothing to support and much to refute recent claims of depths there greater than ." While Fisher missed the eastern basin of the Challenger Deep (for the third time), he did report a deep depression about 150 nautical miles east of the western basin. The 25 March dredge haul at encountered , which pre-shadowed by 22 years the discovery of HMRG Deep/
Sirena Deep
The Sirena Deep, originally named the HMRG Deep, was discovered in 1997 by a team of scientists from Hawaii. Its directly measured depth of is third only to the Challenger Deep and Horizon Deep, currently the deepest known directly measured ...
in 1997. The deepest waters of the HMRG Deep/Serina Deep at are centered at/near , approximately 2.65 km from Fisher's 25 March 1975 dredge haul.
On Scripps Institution of Oceanography's ''INDOPAC Expedition Leg 3'', the chief scientist, Dr. Joseph L. Reid, and oceanographer Arnold W. Mantyla made a hydrocast of a free vehicle (a special-purpose
benthic lander
Benthic landers are observational platforms that sit on the seabed or benthic zone to record physical, chemical or biological activity. The landers are autonomous and have deployment durations from a few days (for biological studies) to several ...
(or "baited camera") for measurements of water temperature and salinity) on 27 May 1976 into the western basin of the Challenger Deep, "Station 21", at at about depth. On ''INDOPAC Expedition Leg 9'', under chief scientist A. Aristides Yayanos, ''Thomas Washington'' spent nine days from 13–21 January 1977 conducting an extensive and detailed investigation of the Challenger Deep, mainly with biological objectives. "Echo soundings were carried out primarily with a 3.5 kHz single-beam system, with a 12 kHz echosounder operated in addition some of the time" (the 12 kHz system was activated for testing on 16 January). A benthic lander was put into the western basin () on 13 January, bottoming at and recovered 50 hours later in damaged condition. Quickly repaired, it was again put down on the 15th to depth at . It was recovered on the 17th with excellent photography of
amphipods
Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far describ ...
(shrimp) from the Challenger Deep’s western basin. The benthic lander was put down for the third and last time on the 17th, at , in the central basin at a depth of . The benthic lander was not recovered and may remain on the bottom in the vicinity of . Free traps and pressure-retaining traps were put down at eight location from 13 to 19 January into the western basin, at depths ranging from . Both the free traps and the pressure-retaining traps brought up good sample amphipods for study. While the ship briefly visited the area of the eastern basin, the expedition did not recognize it as potentially the deepest of the three Challenger Deep basins.
''Thomas Washington'' returned briefly to the Challenger Deep on 17–19 October 1978 during ''Mariana Expedition Leg 5'' under chief scientist James W. Hawkins. The ship tracked to the south and west of the eastern basin, and recorded depths between . Another miss. On ''Mariana Expedition Leg 8'', under chief scientist Yayanos, ''Thomas Washington'' was again involved, from 12–21 December 1978, with an intensive biological study of the western and central basins of the Challenger Deep. Fourteen traps and pressure-retaining traps were put down to depths ranging from ; the greatest depth was at . All of the 10,900-plus m recordings were in the western basin. The depth was furthest east at 142°26.4' E (in the central basin), about 17 km west of the eastern basin. Again, focused efforts on the known areas of extreme depths (the western and central basins) was so tight that the eastern basin again was missed by this expedition.
From 20 to 30 November 1980, ''Thomas Washington'' was on site at the western basin of the Challenger Deep, as part of ''Rama Expedition Leg 7'', again with chief-scientist Dr. A. A. Yayanos. Yayanos directed ''Thomas Washington'' in arguably the most extensive and wide-ranging of all single-beam bathymetric examinations of the Challenger Deep ever undertaken, with dozens of transits of the western basin, and ranging far into the
backarc
The back-arc region is the area behind a volcanic arc. In island volcanic arcs, it consists of back-arc basins of oceanic crust with abyssal depths, which may be separated by remnant arcs, similar to island arcs. In continental arcs, the back- ...
of the Challenger Deep (northward), with significant excursions into the Pacific Plate (southward) and along the trench axis to the east. They hauled eight dredges in the western basin to depths ranging from , and between hauls, cast thirteen free vertical traps. The dredging and traps were for biological investigation of the bottom. In the first successful retrieval of a live animal from the Challenger Deep, on 21 November 1980 in the western basin at , Yayanos recovered a live amphipod from about 10,900 meters depth with a pressurized trap. Once again, other than a brief look into the eastern basin, all bathymetric and biological investigations were into the western basin.
1976–1977 – RV ''Kana Keoki''
On Leg 3 of the Hawaii Institute of Geophysics' (HIG) expedition 76010303, the 156-foot research vessel ''Kana Keoki'' departed Guam primarily for a
seismic
Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...
investigation of the Challenger Deep area, under chief scientist Donald M. Hussong. The ship was equipped with air guns (for seismic reflection soundings deep into the
Earth's mantle
Earth's mantle is a layer of silicate rock between the crust and the outer core. It has a mass of 4.01 × 1024 kg and thus makes up 67% of the mass of Earth. It has a thickness of making up about 84% of Earth's volume. It is predominantly sol ...
),
magnetometer
A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...
,
gravimeter
Gravimetry is the measurement of the strength of a gravitational field. Gravimetry may be used when either the magnitude of a gravitational field or the properties of matter responsible for its creation are of interest.
Units of measurement
Gr ...
, 3.5 kHz and 12 kHz sonar transducers, and precision depth recorders. They ran the Deep from east to west, collecting single beam bathymetry, magnetic and gravity measurements, and employed the air guns along the trench axis, and well into the
backarc
The back-arc region is the area behind a volcanic arc. In island volcanic arcs, it consists of back-arc basins of oceanic crust with abyssal depths, which may be separated by remnant arcs, similar to island arcs. In continental arcs, the back- ...
and
forearc
Forearc is a plate tectonic term referring to a region between an oceanic trench, also known as a subduction zone, and the associated volcanic arc. Forearc regions are present along a convergent margins and eponymously form 'in front of' the vol ...
, from 13 to 15 March 1976. Thence they proceeded south to the
Ontong Java Plateau
The Ontong Java Plateau (OJP) is a massive oceanic plateau located in the southwestern Pacific Ocean, north of the Solomon Islands.
The OJP was formed around (Ma) with a much smaller volcanic event around 90 Ma. Two other southwestern Pacific ...
. All three deep basins of the Challenger Deep were covered, but ''Kana Keoki'' recorded a maximum depth of . Seismic information developed from this survey was instrumental in gaining an understanding of the
subduction
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
of the
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate.
The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...
under the
Philippine Sea Plate
The Philippine Sea Plate or the Philippine Plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part o ...
. In 1977, ''Kana Keoki'' returned to the Challenger Deep area for wider coverage of the forearc and backarc.
1984 – SV ''Takuyo''
The Hydrographic Department, Maritime Safety Agency, Japan (JHOD) deployed the newly commissioned 2,600-ton survey vessel ''Takuyo'' (HL 02) to the Challenger Deep 17–19 February 1984. ''Takuyo'' was the first Japanese ship to be equipped with the new narrowbeam SeaBeammulti-beam sonar echosounder, and was the first
survey ship
A survey vessel is any type of ship or boat that is used for underwater surveys, usually to collect data for mapping or planning underwater construction or mineral extraction. It is a type of research vessel, and may be designed for the purpo ...
with multi-beam capability to survey the Challenger Deep. The system was so new that JHOD had to develop their own software for drawing bathymetric charts based on the SeaBeam digital data. In just three days, they tracked 500 miles of sounding lines, and covered about 140 km of the Challenger Deep with multibeam ensonification. Under chief scientist Hideo Nishida, they used CTD temperature and salinity data from the top of the
water column
A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...
to correct depth measurements, and later conferred with Scripps Institution of Oceanography (including Fisher), and other
GEBCO
The General Bathymetric Chart of the Oceans (GEBCO) is a publicly available bathymetric chart of the world's oceans. The project was conceived with the aim of preparing a global series of charts showing the general shape of the seafloor. Over the ...
experts to confirm their depth correction methodology. They employed a combination of
NAVSAT
The Transit system, also known as NAVSAT or NNSS (for ''Navy Navigation Satellite System''), was the first satellite navigation system to be used operationally. The radio navigation system was primarily used by the U.S. Navy to provide accurat ...
,
LORAN-C
Loran-C is a hyperbolic radio navigation system that allows a receiver to determine its position by listening to low frequency radio signals that are transmitted by fixed land-based radio beacons. Loran-C combined two different techniques to ...
and
OMEGA
Omega (; capital: Ω, lowercase: ω; Ancient Greek ὦ, later ὦ μέγα, Modern Greek ωμέγα) is the twenty-fourth and final letter in the Greek alphabet. In the Greek numeric system/isopsephy (gematria), it has a value of 800. The wo ...
systems for geodetic positioning with accuracy better than . The deepest location recorded was at ; for the first time documenting the eastern basin as the deepest of the three
en echelon
An echelon formation () is a (usually military) formation in which its units are arranged diagonally. Each unit is stationed behind and to the right (a "right echelon"), or behind and to the left ("left echelon"), of the unit ahead. The name of ...
pools. In 1993,
GEBCO
The General Bathymetric Chart of the Oceans (GEBCO) is a publicly available bathymetric chart of the world's oceans. The project was conceived with the aim of preparing a global series of charts showing the general shape of the seafloor. Over the ...
recognized the report as the deepest depth of the world’s oceans. Technological advances such as improved multi-beam sonar would be the driving force in uncovering the mysteries of the Challenger Deep into the future.
1986 – RV ''Thomas Washington''
The Scripps research vessel ''Thomas Washington'' returned to the Challenger Deep in 1986 during the ''Papatua Expedition, Leg 8'', mounting one of the first commercial multi-beam echosounders capable of reaching into the deepest trenches, i.e. the 16-beam Seabeam "Classic". This allowed chief scientist Yayanos an opportunity to transit the Challenger Deep with the most modern depth-sounding equipment available. During the pre-midnight hours of 21 April 1986, the multibeam echosounder produced a map of the Challenger Deep bottom with a
swath
A small waterplane area twin hull, better known by the acronym SWATH, is a catamaran design that minimizes hull cross section area at the sea's surface. Minimizing the ship's volume near the surface area of the sea, where wave energy is located ...
of about 5–7 miles wide. The maximum depth recorded was (location of depth is not available). Yayanos noted: "The lasting impression from this cruise comes from the thoughts of the revolutionary things that Seabeam data can do for deep biology."
1988 – RV ''Moana Wave''
On 22 August 1988, the U.S. Navy-owned 1,000-ton research vessel ''Moana Wave'' (AGOR-22), operated by the Hawaii Institute of Geophysics (HIG),
University of Hawaii
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, th ...
, under the direction of chief scientist Robert C. Thunell from the University of South Carolina, transited northwesterly across the central basin of the Challenger Deep, conducting a single-beam bathymetry track by their 3.5 kHz narrow (30-degs) beam echosounder with a Precision Depth Recorder. In addition to sonar bathymetry, they took 44 gravity cores and 21 box cores of bottom sediments. The deepest echosoundings recorded were , with the greatest depth at 11°22′N 142°25′E in the central basin. This was the first indication that all three basins contained depths in excess of .
1992 – RV ''Hakuhō Maru''
The 3,987-ton Japanese research vessel ''Hakuhō Maru'', an Ocean Research Institute – University of Tokyo sponsored ship, on cruise KH-92-5 cast three Sea-Bird SBE-9 ultra-deep CTD (conductivity-temperature-depth) profilers in a transverse line across the Challenger Deep on 1 December 1992. The center CTD was located at , in the eastern basin, at by the SeaBeam depth recorder and by the CTD. The other two CTDs were cast 19.9 km to the north and 16.1 km to the south. ''Hakuhō Maru'' was equipped with a narrow beam SeaBeam 500 multi-beam echosounder for depth determination, and had an Auto-Nav system with inputs from NAVSAT/NNSS, GPS, Doppler Log, EM log and track display, with a
geodetic positioning
Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), Earth rotation, orientation in space, and Earth's gravity, gravity. The field also incorporates studies of how these properti ...
accuracy approaching . When conducting CTD operations in the Challenger deep, they used the SeaBeam as a single beam depth recorder. At the corrected depth was , and at the depth was ; both in the ''eastern'' basin. This may demonstrate that the basins might not be flat sedimentary pools but rather undulate with a difference of or more. Taira revealed, "We considered that a
trough
Trough may refer to:
In science
* Trough (geology), a long depression less steep than a trench
* Trough (meteorology), an elongated region of low atmospheric pressure
* Trough (physics), the lowest point on a wave
* Trough level (medicine), the l ...
deeper that ''Vitiaz'' record by was detected. There is a possibly that a depth exceeding with a horizontal scale less that the
beam width
The beam diameter or beam width of an electromagnetic beam is the diameter along any specified line that is perpendicular to the beam axis and intersects it. Since beams typically do not have sharp edges, the diameter can be defined in many differ ...
of measurements exists in the Challenger Deep. Since each SeaBeam 2.7-degree beam width sonar ping expands to cover a circular area about in diameter at depth, dips in the bottom that are less than that size would be difficult to detect from a sonar-emitting platform seven miles above.
1996 – RV ''Yokosuka''
For most of 1995 and into 1996, the
Japan Agency for Marine-Earth Science and Technology
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
(JAMSTEC) employed the 4,439-ton Research Vessel ''Yokosuka'' to conduct the testing and workup of the 11,000 meter remotely-operated vehicle (ROV) '' Kaikō'', and the 6,500 meter ROV ''Shinkai.'' It was not until February 1996, during ''Yokosuka'' cruise Y96-06, that ''Kaikō'' was ready for its first full depth dives. On this cruise, JAMSTEC established an area of the Challenger Deep (11°10'N to 11°30'N, by 141°50'E to 143°00'Ewhich later was recognized as containing three separate pools/basins en echelon, each with depths in excess of ) toward which JAMSTEC expeditions would concentrate their investigations for the next two decades. The Yokosuka employed a 151-beam SeaBeam 2112 12 kHz multibeam echosounder, allowing search swaths 12–15 km in width at depth. The depth accuracy of ''Yokosuka'' Seabeam was about 0.1% of water depth (i.e. ± for depth). The ship's dual GPS systems attained geodetic positioning within double digit meter ( or better) accuracy.
1998, 1999 and 2002 – RV ''Kairei''
Cruise KR98-01 sent JAMSTEC's two-year-old the 4,517-ton Deep Sea Research Vessel RV ''Kairei'' south for a quick but thorough depth survey of the Challenger Deep, 11–13 January 1998, under chief scientist Kantaro Fujioka. Tracking largely along the trench axis of 070–250° they made five 80-km bathymetric survey tracks, spaced about 15-km apart, overlapping their SeaBeam 2112-004 (which now allowed sub-bottom profiling penetrating as much as 75 m below the bottom) while gaining gravity and magnetic data covering the entire Challenger Deep: western, central, and eastern basins.
''Kairei'' returned in May 1998, cruise KR98-05, with ROV ''Kaikō'', under the direction of chief scientist Jun Hashimoto with both geophysical and biological goals. Their bathymetric survey from 14–26 May was the most intensive and thorough depth and seismic survey of the Challenger Deep performed to date. Each evening, ''Kaikō'' deployed for about four hours of bottom time for biological-related sampling, plus about seven hours of vertical transit time. When ''Kaikō'' was onboard for servicing, ''Kairei'' conducted bathymetric surveys and observations. ''Kairei'' gridded a survey area about 130 km N–S by 110 km E–W. ''Kaikō'' made six dives (#71–75) all to the same location, (11°20.8' N, 142°12.35' E), near the bottom contour line in the western basin.
The regional bathymetric map made from the data obtained in 1998 shows that the greatest depths in the eastern, central, and western depressions are , , and , respectively, making the eastern depression the deepest of the three.
In 1999, ''Kairei'' revisited the Challenger Deep during cruise KR99-06. The results of the 1998–1999 surveys include the first recognition that the Challenger Deep consists of three "right-stepping en echelon individual basins bounded by the depth contour line. The size of ach ofthe deeps are almost identical, 14–20 km long, 4 km wide". They concluded with the proposal "that these three individual elongated deeps constitute the 'Challenger Deep', and eidentify them as the East, Central and West Deep. The deepest depth we obtained during the swath mapping is in the West Deep (11°20.34' N, 142°13.20 E)." The depth was "obtained during swath mapping ... confirmed in both N–S and E-W swaths." Speed of sound corrections were from XBT to , and CTD below .
The cross track survey of the 1999 ''Kairei'' cruise shows that the greatest depths in the eastern, central, and western depressions are , , and , respectively, which supports the results of the previous survey.
In 2002 ''Kairei'' revisited the Challenger Deep 16–25 October 2002, as cruise KR02-13 (a cooperative Japan-US-South Korea research program) with chief scientist Jun Hashimoto in charge; again with Kazuyoshi Hirata managing the ROV ''Kaikō'' team. On this survey, the size of each of the three basins was refined to 6–10 km long by about 2 km wide and in excess of deep. In marked contrast to the ''Kairei'' surveys of 1998 and 1999, the detailed survey in 2002 determined that the deepest point in the Challenger Deep is located in the eastern basin around , with a depth of , located about southeast of the deepest site determined by the survey vessel ''Takuyo'' in 1984. The 2002 surveys of both the western and eastern basins were tight, with especially meticulous cross-gridding of the eastern basin with ten parallel tracks N–S and E–W less than 250 meters apart. On the morning of 17 October, ROV ''Kaikō'' dive #272 began and recovered over 33 hours later, with the ROV working at the bottom of the western basin for 26 hours (vicinity of 11°20.148' N, 142°11.774 E at ). Five ''Kaikō'' dives followed on a daily basis into the same area to service benthic landers and other scientific equipment, with dive #277 recovered on 25 October. Traps brought up large numbers of amphipods (sea fleas), and cameras recorded holothurians (
sea cucumber
Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuria ...
s), White
polychaete
Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that ...
s (bristle worms), tube worms, and other biological species. During its 1998, 1999 surveys, ''Kairei'' was equipped with a GPS satellite-based
radionavigation
Radio navigation or radionavigation is the application of radio frequencies to determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of radiodetermination.
The basic principles a ...
system. The United States government lifted the GPS selective availability in 2000, so during its 2002 survey, ''Kairei'' had access to non-degraded GPS positional services and achieved single digit meter accuracy in geodetic positioning.
2001 – RV ''Melville''
The 2.516-ton research vessel ''Melville'', at the time operated by the Scripps Institution of Oceanography, took the Cook Expedition, Leg 6 with chief scientist Patricia Fryer of the University of Hawaii from Guam on 10 February 2001 to the Challenger Deep for a survey titled "Subduction Factory Studies in the Southern Mariana", including HMR-1 sonar mapping, magnetics, gravity measurements, and dredging in the Mariana arc region. They covered all three basins, then tracked lines of bathymetry East-West, stepping northward from the Challenger Deep in sidesteps, covering more than north into the backarc with overlapping swaths from their SeaBeam 2000 12 kHz multi-beam echosounder and MR1 towed system. They also gathered
magnetic
Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particle ...
and
gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
information, but no seismic data. Their primary survey instrument was the MR1 towed sonar, a shallow-towed 11/12 kHz bathymetric
sidescan sonar
Side-scan sonar (also sometimes called side scan sonar, sidescan sonar, side imaging sonar, side-imaging sonar and bottom classification sonar) is a category of sonar system that is used to efficiently create an image of large areas of the sea ...
developed and operated by the Hawaii Mapping Research Group (HMRG), a research and operational group within University of Hawaii's School of Ocean and Earth Science and Technology (SOEST) and the Hawaii Institute of Geophysics and Planetology (HIGP). The MR1 is full-ocean-depth capable, and provides both bathymetry and sidescan data.
Leg 7 of the Cook Expedition continued the MR-1 survey of the Mariana Trench backarc from 4 March to 12 April 2001 under chief scientist Sherman Bloomer of
Oregon State University
Oregon State University (OSU) is a public land-grant, research university in Corvallis, Oregon. OSU offers more than 200 undergraduate-degree programs along with a variety of graduate and doctoral degrees. It has the 10th largest engineering co ...
.
2009 – RV ''Kilo Moana''
In May/June 2009 the US Navy-owned 3,064-ton twin-hulled research vessel ''Kilo Moana'' (T-AGOR 26) was sent to the Challenger Deep area to conduct research. ''Kilo Moana'' is civilian-manned and operated by SOEST. It is equipped with two multibeam echosounders with sub-bottom profiler add-ons (the 191-beam 12 kHz Kongsberg Simrad EM120 with SBP-1200, capable of accuracies of 0.2–0.5% of water depth across the entire swath),
gravimeter
Gravimetry is the measurement of the strength of a gravitational field. Gravimetry may be used when either the magnitude of a gravitational field or the properties of matter responsible for its creation are of interest.
Units of measurement
Gr ...
, and
magnetometer
A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...
. The EM-120 uses 1 by 1 degree sonar-emissions at the sea surface. Each 1 degree beam width sonar ping expands to cover a circular area about in diameter at depth. Whilst mapping the Challenger Deep the sonar equipment indicated a maximum depth of at an undisclosed position. Navigation equipment includes the Applanix POS MV320 V4, rated at accuracies of 0.5–2 m. RV ''Kilo Moana'' was also used as the support ship of the hybrid remotely operated underwater vehicle (HROV) ''
Nereus
In Greek mythology, Nereus ( ; ) was the eldest son of Pontus (the Sea) and Gaia ( the Earth), with Pontus himself being a son of Gaia. Nereus and Doris became the parents of 50 daughters (the Nereids) and a son ( Nerites), with whom Nereus ...
'' that dove three times to the Challenger Deep bottom during the May/June 2009 cruise and did not confirm the sonar established maximum depth by its support ship.
2009 – RV ''Yokosuka''
Cruise YK09-08 brought the JAMSTEC 4,429-ton research vessel ''Yokosuka'' back to the
Mariana Trough
The Mariana Trough is an active back-arc basin in the western Pacific Ocean . It is an integral part of the Izu–Bonin–Mariana Arc system.
Location and Bathymetry
The Mariana Trough stretches 1300 km from north to south, about the dista ...
and to the Challenger Deep June–July 2009. Their mission was a two-part program: surveying three
hydrothermal vent
A hydrothermal vent is a fissure on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspot ...
sites in the southern Mariana Trough backarc basin near 12°57'N, 143°37'E about 130 nmi northeast of the central basin of the Challenger Deep, using the autonomous underwater vehicle ''Urashima''. AUV ''Urashima'' dives #90–94, were to a maximum depth of 3500 meters, and were successful in surveying all three sites with a Reson SEABAT7125AUV multibeam echosounder for bathymetry, and multiple water testers to detect and map trace elements spewed into the water from hydrothermal vents, white smokers, and hot spots. Kyoko OKINO from the Ocean Research Institute, University of Tokyo, was
principal investigator
In many countries, the term principal investigator (PI) refers to the holder of an independent grant and the lead researcher for the grant project, usually in the sciences, such as a laboratory study or a clinical trial. The phrase is also often us ...
for this aspect of the cruise.
The second goal of the cruise was to deploy a new "10K free fall camera system" called ''Ashura'', to sample sediments and biologics at the bottom of the Challenger Deep. The principal investigator at the Challenger Deep was Taishi Tsubouchi of JAMSTEC. The lander ''Ashura'' made two descents: on the first, 6 July 2009, ''Ashura'' bottomed at at . The second descent (on 10 July 2009) was to at . The 270 kg ''Ashura'' was equipped with multiple baited traps, a HTDV video camera, and devices to recover sediment, water, and biological samples (mostly amphipods at the bait, and bacteria and fungus from the sediment and water samples).
2010 – USNS ''Sumner''
On 7 October 2010, further sonar mapping of the Challenger Deep area was conducted by the US Center for Coastal & Ocean Mapping/Joint Hydrographic Center (CCOM/JHC) aboard the 4.762-ton ''Sumner''. The results were reported in December 2011 at the annual
American Geophysical Union
The American Geophysical Union (AGU) is a 501(c)(3) nonprofit organization of Earth, atmospheric, ocean, hydrologic, space, and planetary scientists and enthusiasts that according to their website includes 130,000 people (not members). AGU's act ...
fall meeting. Using a Kongsberg Maritime EM 122 multi-beam echosounder system coupled to positioning equipment that can determine latitude and longitude up to accuracy, from thousands of individual soundings around the deepest part the CCOM/JHC team preliminary determined that the Challenger Deep has a maximum depth of at , with an estimated vertical uncertainty of ± at two
standard deviation
In statistics, the standard deviation is a measure of the amount of variation or dispersion of a set of values. A low standard deviation indicates that the values tend to be close to the mean (also called the expected value) of the set, while ...
s (i.e. ≈ 95.4%) confidence level. A secondary deep with a depth of was located at approximately to the east at in the eastern basin of the Challenger Deep.
2010 – RV ''Yokosuka''
JAMSTEC returned ''Yokosuka'' to the Challenger Deep with cruise YK10-16, 21–28 November 2010. The chief scientist of this joint Japanese-Danish expedition was Hiroshi Kitazato of the Institute of Biogeosciences, JAMSTEC. The cruise was titled "Biogeosciences at the Challenger Deep: relict organisms and their relations to biogeochemical cycles". The Japanese teams made five deployments of their 11,000-meter camera system (three to 6,000 meters – two into the central basin of the Challenger Deep) which returned with 15 sediment cores, video records and 140 scavenging amphipod specimens. The Danish Ultra Deep Lander System was employed by Ronnie Glud et al on four casts, two into the central basin of the Challenger Deep and two to 6,000 m some 34 nmi west of the central basin. The deepest depth recorded was on 28 November 2010 – camera cast CS5 – }, at a corrected depth of (the central basin).
2013 – RV ''Yokosuka''
With JAMSTEC Cruises YK13-09 and YK13-12, ''Yokosuka'' hosted chief scientist Hidetaka Nomaki for a trip to New Zealand waters (YK13-09), with the return cruise identified as YK13-12. The project name was QUELLE2013; and the cruise title was: "In situ experimental & sampling study to understand abyssal biodiversity and biogeochemical cycles". They spent one day on the return trip at the Challenger Deep to obtain DNA/RNA on the large amphipods inhabiting the Deep (''Hirondellea gigas''). Hideki Kobayashi (Biogeos, JAMSTEC) and team deployed a benthic lander on 23 November 2013 with eleven baited traps (three bald, five covered by insulating materials, and three automatically sealed after nine hours) into the central basin of the Challenger Deep at , depth . After an eight-hour, 46-minute stay at the bottom, they recovered some 90 individual ''Hirondellea gigas''.
2014 – RV ''Kairei''
JAMSTEC deployed ''Kairei'' to the Challenger Deep again 11–17 January 2014, under the leadership of chief scientist Takuro Nunora. The cruise identifier was KR14-01, titled: "Trench
biosphere
The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also be ...
expedition for the Challenger Deep, Mariana Trench". The expedition sampled at six stations transecting the central basin, with only two deployments of the "11-K camera system" lander for sediment cores and water samples to "Station C" at the deepest depth, i.e. , at . The other stations were investigated with the "Multi-core" lander, both to the backarc northward, and to the Pacific Plate southward. The 11,000-meter capable crawler-driven ROV ''ABIMSO'' was sent to 7,646 m depth about 20 nmi due north of the central basin (ABISMO dive #21) specifically to identify possible hydrothermal activity on the north slope of the Challenger Deep, as suggested by findings from ''Kairei'' cruise KR08-05 in 2008. ''AMISMO'' dives #20 and #22 were to 7,900 meters about 15 nmi north of the deepest waters of the central basin. Italian researchers under the leadership of Laura Carugati from the
Polytechnic University of Marche
Marche Polytechnic University or Polytechnic University of the Marches (Italian ''Università Politecnica delle Marche'') is a public university in Ancona, Italy. It offers undergraduate and graduate degrees in Agriculture, Engineering, Economics, ...
, Italy (UNIVPM) were investigating the dynamics in virus/
prokaryotes
A prokaryote () is a single-celled organism that lacks a nucleus and other membrane-bound organelles. The word ''prokaryote'' comes from the Greek πρό (, 'before') and κάρυον (, 'nut' or 'kernel').Campbell, N. "Biology:Concepts & Connec ...
interactions in the Mariana Trench.
2014 – RV ''Falkor''
From 16–19 December 2014, the
Schmidt Ocean Institute
Schmidt Ocean Institute (SOI) is a 501(c)(3) non-profit operating foundation established in March 2009 by Eric Schmidt and Wendy Schmidt. The Institute's goal is to advance innovative oceanographic research and discovery through technological adv ...
's 2,024-ton research vessel ''
Falkor
This article lists character information from the 1979 novel ''The Neverending Story'' by Michael Ende and the film adaptations of the same name.
Bastian Balthazar Bux
Bastian Balthazar Bux is a shy and bookish boy, 10 or 11 years old, who ...
'', under chief scientist Douglas Bartlett from the Scripps Institution of Oceanography, deployed four different untethered instruments into the Challenger Deep for seven total releases. Four landers were deployed on 16 December into the central basin: the baited video-equipped lander ''Leggo'' for biologics; the lander ''ARI'' to for water chemistry; and the probes ''Deep Sound 3'' and ''Deep Sound 2''. Both Deep Sound probes recorded acoustics floating at depth, until ''Deep Sound 3'' imploded at the depth of (about above the bottom) at . The ''Deep Sound 2'' recorded the implosion of ''Deep Sound 3'', providing a unique recording of an implosion within the Challenger Deep depression. In addition to the loss of the ''Deep Sound 3'' by implosion, the lander ''ARI'' failed to respond upon receiving its instruction to drop weights, and was never recovered. On 16/17 December, ''Leggo'' was returned to the central basin baited for amphipods. On the 17th, RV ''Falkor'' relocated 17 nms eastward to the eastern basin, where they again deployed both the ''Leggo'' (baited and with its full camera load), and the ''Deep Sound 2''. ''Deep Sound 2'' was programmed to drop to and remain at that depth during its recording of sounds within the trench. On 19 December ''Leggo'' landed at at a uncorrected depth of according to its pressure sensor readings. This reading was corrected to depth. ''Leggo'' returned with good photography of amphipods feeding on the lander’s mackerel bait and with sample amphipods. ''Falknor'' departed the Challenger Deep on 19 December en route the
Pacific Marine Environmental Laboratory
The Pacific Marine Environmental Laboratory (PMEL) is a federal laboratory in the National Oceanic and Atmospheric Administration (NOAA) Office of Oceanic and Atmospheric Research (OAR). It is one of seven NOAA Research Laboratories (RLs). The PM ...
(PMEL), the
University of Washington
The University of Washington (UW, simply Washington, or informally U-Dub) is a public research university in Seattle, Washington.
Founded in 1861, Washington is one of the oldest universities on the West Coast; it was established in Seattle a ...
, and Oregon State University, in deploying PMEL's "Full-Ocean Depth Mooring", a 45-meter-long moored deep-ocean
hydrophone
A hydrophone ( grc, ὕδωρ + φωνή, , water + sound) is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates an electric potenti ...
and pressure sensor array into the western basin of the Challenger Deep. A 6-hour descent into the western basin anchored the array at of water depth, at , about 1 km northeast of ''Sumner'' deepest depth, recorded in 2010. After 16 weeks, the moored array was recovered on 2–4 November 2015. "Observed sound sources included earthquake signals (T phases), baleen and odontocete cetacean vocalizations, ship propeller sounds, airguns, active sonar and the passing of a Category 4 typhoon." The science team described their results as "the first multiday, broadband record of ambient sound at Challenger Deep, as well as only the fifth direct depth measurement".
2016 – RV ''Xiangyanghong 09''
The 3,536-ton research vessel ''Xiangyanghong 09'' deployed on Leg II of the 37th China Cruise Dayang (DY37II) sponsored by the National Deep Sea Center, Qingdao and the Institute of Deep-Sea Science and Engineering,
Chinese Academy of Sciences
The Chinese Academy of Sciences (CAS); ), known by Academia Sinica in English until the 1980s, is the national academy of the People's Republic of China for natural sciences. It has historical origins in the Academia Sinica during the Republ ...
(Sanya, Hainan), to the Challenger Deep western basin area (11°22' N, 142°25' E) 4 June – 12 July 2016. As the mother ship for China’s manned deep submersible ''Jiaolong'', the expedition carried out an exploration of the Challenger Deep to investigate the geological, biological, and chemical characteristics of the
hadal zone
The hadal zone, also known as the hadopelagic zone, is the deepest region of the ocean, lying within oceanic trenches. The hadal zone ranges from around below sea level, and exists in long, narrow, topographic V-shaped depressions.
The cumula ...
. The diving area for this leg was on the southern slope of the Challenger Deep, at depths from about . The submersible completed nine manned dives on the northern backarc and south area (
Pacific plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate.
The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...
) of the Challenger Deep to depths from . During the cruise, ''Jiaolong'' regularly deployed gas-tight samplers to collect water near the sea bottom. In a test of navigational proficiency, ''Jiaolong'' used an Ultra-Short Base Line (USBL) positioning system at a depth more than to retrieve sampling bottles.
2016 – RV ''Tansuo 01''
From 22 June to 12 August 2016 (cruises 2016S1 and 2016S2), the Chinese Academy of Sciences' 6,250-ton submersible support ship ''Tansuo 1'' (meaning: to explore) on her maiden voyage deployed to the Challenger Deep from her home port of Sanya, Hainan Island. On 12 July 2016, the ROV ''Haidou-1'' dived to a depth of in the Challenger Deep area. They also cast a free-drop lander, rated free-drop ocean-floor seismic instruments (deployed to ), obtained sediment core samples, and collected over 2000 biological samples from depth ranging from . The ''Tansuo 01'' operated along the 142°30.00' longitude line, about 30 nmi east of the earlier DY37II cruise survey (see ''Xiangyanghong 09'' above).
GEOMAR Helmholtz Centre for Ocean Research Kiel
The GEOMAR - Helmholtz Centre for Ocean Research Kiel (GEOMAR), former ''Leibniz Institute of Marine Sciences'' (German: ''Leibniz-Institut für Meereswissenschaften'', IFM-GEOMAR), is a research institute in Kiel, Germany. It was formed in 2004 ...
aboard the 8,554-ton Deep Ocean Research Vessel ''Sonne''. The results were reported in 2017. Using a Kongsberg Maritime EM 122 multi-beam echosounder system coupled to positioning equipment that can determine latitude and longitude the team determined that the Challenger Deep has a maximum depth of at (), with an estimated vertical uncertainty of ± at one standard deviation (≈ 68.3%) confidence level. The analysis of the sonar survey offered a grid resolution at bottom depth, so small dips in the bottom that are less than that size would be difficult to detect from the 0.5 by 1 degree sonar-emissions at the sea surface. Each 0.5-degree beam width sonar ping expands to cover a circular area about in diameter at depth. The horizontal position of the grid point has an uncertainty of ±, depending on along-track or across-track direction. This depth () and position (about to the northeast) measurements differ significantly from the deepest point determined by the Gardner et al. (2014) study. The observed depth discrepancy with the 2010 sonar mapping and Gardner et al 2014 study are related to the application of differing sound velocity profiles, which are essential for accurate depth determination. ''Sonne'' used CTD casts about 1.6 km west of the deepest sounding to near the bottom of the Challenger Deep that were used for sound velocity profile calibration and optimization. Likewise the impact of using different projections, datum and ellipsoids during data acquisition can cause positional discrepancies between surveys.
2016 – RV ''Shyian 3''
In December 2016, the CAS 3,300-ton research vessel ''Shiyan 3'' deployed 33 broadband seismometers onto both the backarc northwest of the Challenger Deep, and onto the near southern Pacific Plate to the southeast, at depths of up to . This cruise was part of a $12 million Chinese-U.S. initiative, led by co-leader Jian Lin of the
Woods Hole Oceanographic Institution
The Woods Hole Oceanographic Institution (WHOI, acronym pronounced ) is a private, nonprofit research and higher education facility dedicated to the study of marine science and engineering.
Established in 1930 in Woods Hole, Massachusetts, it i ...
; a 5-year effort (2017–2021) to image in fine detail the rock layers in and around the Challenger Deep.
2016 – RV ''Zhang Jian''
The newly launched 4,800-ton research vessel (and mothership for the ''Rainbow Fish'' series of deep submersibles), the ''Zhang Jian'' departed
Shanghai
Shanghai (; , , Standard Mandarin pronunciation: ) is one of the four direct-administered municipalities of the People's Republic of China (PRC). The city is located on the southern estuary of the Yangtze River, with the Huangpu River flow ...
on 3 December. Their cruise was to test three new deep-sea landers, one unmanned search submersible and the new ''Rainbow Fish'' 11,000-meter manned deep submersible, all capable of diving to 10,000 meters. From 25 to 27 December, three deep-sea landing devices descended into the trench. The first Rainbow Fish lander took photographs, the second took sediment samples, and the third took biological samples. All three landers reached over 10,000 meters, and the third device brought back 103 amphipods. Cui Weicheng, director of Hadal Life Science Research Center at
Shanghai Ocean University
Shanghai Ocean University () is a public university in Shanghai, China.
The university changed its name to the current name on 6 May 2008, authorized by the Ministry of Education The People's Republic of China, and the whole school was to b ...
, led the team of scientists to carry out research at the Challenger Deep in the Mariana Trench. The ship is part of China’s national marine research fleet but is owned by a Shanghai marine technology company.
2017 – RV ''Tansuo-1''
CAS' Institute of Deep-sea Science and Engineering sponsored ''Tansuo-1'' return to the Challenger Deep 20 January – 5 February 2017 (cruise TS03) with baited traps for capture of fish and other macrobiology near the Challenger and Sirena Deeps. On 29 January they recovered photography and samples of a new species of snailfish from the Northern slope of the Challenger Deep at , newly designated ''Pseudoliparis swirei''. They also placed four or more CTD casts into the ''central'' and ''eastern'' basins of the Challenger Deep, as part of the World Ocean Circulation Experiment (WOCE).
2017 – RV ''Shinyo Maru''
Tokyo University of Marine Science and Technology
, abbreviated as , is a national university in Japan. The main campus (Shinagawa Campus) is located in Minato, Tokyo and another campus (Etchujima Campus) is in Kōtō, Tokyo.
History
The university was established in 2003 with a merger of ...
dispatched the research vessel ''Shinyo Maru'' to the Mariana Trench from 20 January to 5 February 2017 with baited traps for capture of fish and other macrobiology near the Challenger and Sirena Deeps. On 29 January they recovered photography and samples of a new species of snailfish from the Northern slope of the Challenger Deep at , which has been newly designated ''
Pseudoliparis swirei
''Pseudoliparis swirei'', the Mariana snailfish or Mariana hadal snailfish, is a species of snailfish found at hadal depths in the Mariana Trench in the western Pacific Ocean. It is known from a depth range of , including a capture at the deepest ...
''.
2017 – RV ''Kexue 3''
Water samples were collected at the Challenger Deep from 11 layers of the Mariana Trench in March 2017. Seawater samples from 4 to 4,000 m were collected by Niskin bottles mounted to a Seabird SBE25 CTDs; whereas water samples at depths from 6,050 m to 8,320 m were collected by a self-designed acoustic-controlled full ocean depth water samplers. In this study, scientists studied the RNA of pico- and nano-plankton from the surface to the hadal zone.
2017 – RV ''Kairei''
JAMSTEC deployed ''Kairei'' to the Challenger Deep in May 2017 for the express purpose of testing the new full-ocean depth ROV ''UROV11K'' (Underwater ROV 11,000-meter-capable), as cruise KR 17-08C, under chief scientist Takashi Murashima. The cruise title was: "Sea trial of a full depth ROV ''UROV11K'' system in the Mariana Trench". ''UROV11K'' carried a new 4K High Definition video camera system, and new sensors to monitor the hydrogen-sulfide, methane, oxygen, and hydrogen content of the water. Unfortunately, on ''UROV11K'' ascent from (at about 11°22.30’N 142°35.8 E, in the ''eastern'' basin) on 14 May 2017, the ROV's buoyancy failed at depth, and all efforts to retrieve the ROV were unsuccessful. The rate of descent and drift is not available, but the ROV bottomed to the east of the deepest waters of the eastern basin as revealed by the ship's maneuvering on 14 May. Murashima then directed the Kairei to a location about 35 nmi east of the eastern basin of the Challenger Deep to test a new "Compact Hadal Lander" which made three descents to depths from 7,498 to 8,178 m for testing the Sony 4K camera and for photography of fish and other macro-biologics.
2018 – RV ''Shen Kuo''
On its maiden voyage, the 2,150-ton twin-hulled scientific research vessel ''Shen Kuo'' (also ''Shengkuo'', ''Shen Ko'', or ''Shen Quo''), departed Shanghai on 25 November 2018 and returned 8 January 2019. They operated in the Mariana Trench area, and on 13 December tested a system of underwater navigation at a depth exceeding 10,000 metres, during a field trial of the ''Tsaihungyuy'' (ultra-short baseline) system. Project leader Tsui Veichen stated that, with the tsaihungyuy equipment at depth, it was possible to obtain a signal and determine exact
geolocation
Geopositioning, also known as geotracking, geolocalization, geolocating, geolocation, or geoposition fixing, is the process of determining or estimating the geographic position of an object.
Geopositioning yields a set of Geographic coordinate s ...
s. The research team from
Shanghai Ocean University
Shanghai Ocean University () is a public university in Shanghai, China.
The university changed its name to the current name on 6 May 2008, authorized by the Ministry of Education The People's Republic of China, and the whole school was to b ...
and
Westlake University
Westlake University ( zh, 西湖大学) is a private research university in Hangzhou, Zhejiang, China, founded in October 2018.
Westlake University is often being described as “Caltech of China” or "China's Caltech".
Westlake University ra ...
was led by Cui Weicheng, director of Shanghai Ocean University’s Hadal Science and Technology Research Center (HSRC).
The equipment to be tested included a manned submersible (not full ocean depth – depth achieved not available) and two deep-sea landers, all capable of diving to depths of 10,000 meters, as well as a ROV that can go to 4,500 meters. They took photographs and obtained samples from the trench, including water, sediment, macro-organisms and micro-organisms. Cui says, "If we can take photos of fish more than 8,145 meters under water, ... we will break the current world record. We will test our new equipment including the landing devices. They are second generation. The first generation could only take samples in one spot per dive, but this new second generation can take samples at different depths in one dive. We also tested the ultra short baseline acoustic positioning system on the manned submersible, the future of underwater navigation."
2019 – RV ''Sally Ride''
In November 2019, as cruise SR1916, a NIOZ team led by chief scientist Hans van Haren, with Scripps technicians, deployed to the Challenger Deep aboard the 2,641-ton research vessel , to recover a mooring line from the western basin of the Challenger Deep. The long mooring line in the Challenger Deep consisted of top-floatation positioned around depth, two sections of Dyneema neutrally buoyant line, two Benthos acoustic releases and two sections of self-contained instrumentation to measure and store current, salinity and temperature. Around the depth position two current meters were mounted below a long array of 100 high-resolution temperature sensors. In the lower position starting above the sea floor 295 specially designed high-resolution temperature sensors were mounted, the lowest of which was above the trench floor. The mooring line was deployed and left by the NIOZ team during the November 2016 RV ''Sonne'' expedition with the intention to be recovered in late 2018 by ''Sonne''. The acoustic commanded release mechanism near the bottom of the Challenger Deep failed at the 2018 attempt. RV ''Sally Ride'' was made available exclusively for a final attempt to retrieve the mooring line before the release mechanism batteries expired. ''Sally Ride'' arrived at the Challenger Deep on 2 November. This time a 'deep release unit' lowered by one of ''Sally Ride'' winch-cables to around 1,000 m depth pinged release commands and managed to contact the near-bottom releases. After being nearly three years submerged, mechanical problems had occurred in 15 of the 395 temperature sensors. The first results indicate the occurrence of
internal wave
Internal waves are gravity waves that oscillate within a fluid medium, rather than on its surface. To exist, the fluid must be stratified: the density must change (continuously or discontinuously) with depth/height due to changes, for example, in ...
s in the Challenger Deep.
Study of the depth and location of the Challenger Deep
Since May 2000, with the help of non-degraded signal
satellite navigation
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pr ...
, civilian surface vessels equipped with professional dual-frequency capable satellite navigation equipment can measure and establish their geodetic position with an accuracy in the order of meters to tens of meters whilst the western, central and eastern basins are kilometers apart.
In 2014, a study was conducted regarding the determination of the depth and location of the Challenger Deep based on data collected previous to and during the 2010 sonar mapping of the Mariana Trench with a Kongsberg Maritime EM 122 multibeam echosounder system aboard USNS ''Sumner''. This study by James. V. Gardner et al. of the Center for Coastal & Ocean Mapping-Joint Hydrographic Center (CCOM/JHC), Chase Ocean Engineering Laboratory of the University of New Hampshire splits the measurement attempt history into three main groups: early single-beam echo sounders (1950s–1970s), early multibeam echo sounders (1980s – 21st century), and modern (i.e., post-GPS, high-resolution) multibeam echo sounders. Taking uncertainties in depth measurements and position estimation into account the raw data of the 2010 bathymetry of the Challenger Deep vicinity consisting of 2,051,371 soundings from eight survey lines was analyzed. The study concludes that with the best of 2010 multibeam echosounder technologies after the analysis a depth uncertainty of ± (95% confidence level) on 9 degrees of freedom and a positional uncertainty of ± ( 2drms) remain and the location of the deepest depth recorded in the 2010 mapping is at . The depth measurement uncertainty is a composite of measured uncertainties in the spatial variations in sound-speed through the water volume, the ray-tracing and bottom-detection algorithms of the multibeam system, the accuracies and calibration of the motion sensor and navigation systems, estimates of spherical spreading, attenuation throughout the water volume, and so forth.
Both the RV ''Sonne'' expedition in 2016, and the RV ''Sally Ride'' expedition in 2019 expressed strong reservations concerning the depth corrections applied by the Gardner et al. study of 2014, and serious doubt concerning the accuracy of the deepest depth calculated by Gardner (in the ''western'' basin), of after analysis of their multibeam data on a grid. Dr. Hans van Haren, chief scientist on the RV ''Sally Ride'' cruise SR1916, indicated that Gardner's calculations were too deep due to the "sound velocity profiling by Gardner et al. (2014)."
In 2018-2019, the deepest points of each ocean were mapped using a full‐ocean depth Kongsberg EM 124 multibeam echosounder aboard ''DSSV Pressure Drop''. In 2021, a data paper was published by Cassandra Bongiovanni, Heather A. Stewart and Alan J. Jamieson regarding the gathered data donated to GEBCO. The deepest depth recorded in the 2019 Challenger Deep sonar mapping was ± at in the eastern basin. This depth closely agrees with the deepest point ( ±) determined by the Van Haren et al. sonar bathymetry. The geodetic position of the deepest depth according to the Van Haren et al. significantly differs (about to the west) with the 2021 paper. After post-processing the initial depth estimates by application of a full-ocean depth sound velocity profile Bongiovanni et al. report an (almost) as deep point at in the western basin that geodetically differs about with the deepest point position determined by Van Haren et al. ( in the western basin). After analysis of their multibeam data on a grid, the Bongiovanni et al. 2021 paper states the technological accuracy does not currently exist on low-frequency ship-mounted sonars required to determine which location was truly the deepest, nor does it currently exist on deep-sea pressure sensors.
In 2021, a study by Samuel F. Greenaway, Kathryn D. Sullivan, Samuel H. Umfress, Alice B. Beittel and Karl D. Wagner was published presenting a revised estimate of the maximum depth of the Challenger Deep based on a series of submersible dives conducted in June 2020. These depth estimates are derived from acoustic echo sounding profiles referenced to in-situ direct pressure measurements and corrected for observed oceanographic properties of the water-column, atmospheric pressure, gravity and gravity-gradient anomalies, and water-level effects. The study concludes according to their calculations the deepest observed seafloor depth was ± below mean sea level at a 95% condidence level at in the eastern basin. For this estimate, the error term is dominated by the uncertainty of the employed pressure sensor, but Greenaway et al. show that the gravity correction is also substantial. The Greenaway et al. study compares its results with other recent acoustic and pressure-based measurements for the Challenger Deep and concludes the deepest depth in the western basin is very nearly as deep as the eastern basin. The disagreement between the maximum depth estimates and their geodetic positions between post-2000 published depths however exceed the accompanying margins of uncertainty, raising questions regarding the measurements or the reported uncertainties.
Another 2021 paper by Scott Loranger, David Barclay and Michael Buckingham, besides a December 2014 implosion shock wave based depth estimate of , which is among the deepest estimated depths, also treatises the differences between various maximum depth estimates and their geodetic positions.
Direct measurements
The 2010 maximal sonar mapping depths reported by Gardner et.al. in 2014 and Greenaway et al. study in 2021 have not been confirmed by direct descent (pressure gauge/manometer) measurements at full-ocean depth. Expeditions have reported direct measured maximal depths in a narrow range.
For the ''western'' basin deepest depths were reported as by in 1960 and ± by ''
DSV Limiting Factor
A deep-submergence vehicle (DSV) is a deep-diving crewed submersible that is self-propelled. Several navies operate vehicles that can be accurately described as DSVs. DSVs are commonly divided into two types: research DSVs, which are used for ex ...
'' in June 2020.
For the ''central'' basin the greatest reported depth is ± by ''
DSV Limiting Factor
A deep-submergence vehicle (DSV) is a deep-diving crewed submersible that is self-propelled. Several navies operate vehicles that can be accurately described as DSVs. DSVs are commonly divided into two types: research DSVs, which are used for ex ...
'' in June 2020.
For the ''eastern'' basin deepest depths were reported as by ROV in 1995, by ROV ''Nereus'' in 2009, by in 2012, by
benthic lander
Benthic landers are observational platforms that sit on the seabed or benthic zone to record physical, chemical or biological activity. The landers are autonomous and have deployment durations from a few days (for biological studies) to several ...
"Leggo" in May 2019, and ± by ''
DSV Limiting Factor
A deep-submergence vehicle (DSV) is a deep-diving crewed submersible that is self-propelled. Several navies operate vehicles that can be accurately described as DSVs. DSVs are commonly divided into two types: research DSVs, which are used for ex ...
'' in May 2019.
Descents
Crewed descents
1960 – ''Trieste''
On 23 January 1960, the Swiss-designed ''Trieste'', originally built in Italy and acquired by the
U.S. Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage o ...
, supported by the USS ''Wandank'' (ATF 204) and escorted by the USS ''Lewis'' (DE 535), descended to the ocean floor in the trench manned by
Jacques Piccard
Jacques Piccard (28 July 19221 November 2008) was a Swiss oceanographer and engineer, known for having developed underwater submarines for studying ocean currents. In the Challenger Deep, he and Lt. Don Walsh of the United States Navy were the ...
(who co-designed the submersible along with his father, Auguste Piccard) and USN Lieutenant
Don Walsh
Don Walsh (born November 2, 1931) is an American oceanographer, explorer and marine policy specialist. He and Jacques Piccard were aboard the bathyscaphe ''Trieste'' when it made a record maximum descent into the Challenger Deep on January 2 ...
. Their crew compartment was inside a spherical pressure vessel – measuring 2.16 metres in diameter suspended beneath a buoyancy tank 18.4 metres in length – which was a heavy-duty replacement (of the Italian original) built by
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
Steel Works of
Essen
Essen (; Latin: ''Assindia'') is the central and, after Dortmund, second-largest city of the Ruhr, the largest urban area in Germany. Its population of makes it the fourth-largest city of North Rhine-Westphalia after Cologne, Düsseldorf and D ...
,
Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
. The
steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
walls were 12.7 cm thick and designed to withstand pressure of up to .
Their descent took almost five hours and the two men spent barely twenty minutes on the ocean floor before undertaking the three-hour-and-fifteen-minute ascent. Their early departure from the
ocean floor
The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'.
The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...
was due to their concern over a crack in the outer window caused by the temperature differences during their descent.
''Trieste'' dove at/near , bottoming at ± into the Challenger Deep's ''western'' basin, as measured by an onboard
manometer
Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressur ...
. Another source states the measured depth at the bottom was measured with a
manometer
Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressur ...
at ±.
Navigation of the support ships was by celestial and
LORAN-C
Loran-C is a hyperbolic radio navigation system that allows a receiver to determine its position by listening to low frequency radio signals that are transmitted by fixed land-based radio beacons. Loran-C combined two different techniques to ...
with an accuracy of or less. Fisher noted that the ''Triestes reported depth "agrees well with the sonic sounding."
2012 – ''Deepsea Challenger''
On 26 March 2012 (local time), Canadian film director
James Cameron
James Francis Cameron (born August 16, 1954) is a Canadian filmmaker. A major figure in the post-New Hollywood era, he is considered one of the industry's most innovative filmmakers, regularly pushing the boundaries of cinematic capability w ...
made a solo manned descent in the DSV ''Deepsea Challenger'' to the bottom of the Challenger Deep.
At approximately 05:15 ChST on 26 March (19:15 UTC on 25 March), the descent began.
At 07:52 ChST (21:52 UTC), ''Deepsea Challenger'' arrived at the bottom. The descent lasted 2 hours and 36 minutes and the recorded depth was when ''Deepsea Challenger'' touched down.
Cameron had planned to spend about six hours near the ocean floor exploring but decided to start the ascent to the surface after only 2 hours and 34 minutes. The time on the bottom was shortened because a hydraulic fluid leak in the lines controlling the manipulator arm obscured the visibility out the only viewing port. It also caused the loss of the submersible's starboard thrusters. At around 12:00 ChST (02:00 UTC on 26 March), the Deepsea Challenger website says the sub resurfaced after a 90-minute ascent, although Paul Allen's tweets indicate the ascent took only about 67 minutes. During a post-dive press conference Cameron said: "I landed on a very soft, almost gelatinous flat plain. Once I got my bearings, I drove across it for quite a distance ... and finally worked my way up the slope." The whole time, Cameron said, he didn't see any fish, or any living creatures more than an inch (2.54 cm) long: "The only free swimmers I saw were small
amphipods
Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far describ ...
The Five Deeps Expedition objective was to thoroughly map and visit the deepest points of all five of the world's oceans by the end of September 2019. On 28 April 2019, explorer
Victor Vescovo
Victor Lance Vescovo (born 1966) is an American private equity investor, retired naval officer, space tourist and undersea explorer.
He is a co-founder and managing partner of private equity company Insight Equity Holdings. Vescovo achieved the ...
descended to the "Eastern Pool" of the Challenger Deep in the Deep-Submergence Vehicle '' DSV ''Limiting Factor'''' (a Triton 36000/2 model submersible). Between 28 April and 4 May 2019, the ''Limiting Factor'' completed four dives to the bottom of Challenger Deep. The fourth dive descended to the slightly less deep "Central Pool" of the Challenger Deep (crew: Patrick Lahey, Pilot; John Ramsay, Sub Designer). The Five Deeps Expedition estimated maximum depths of ± and ± at () by direct CTD pressure measurements and a survey of the operating area by the support ship, the Deep Submersible Support Vessel '' DSSV ''Pressure Drop'''', with a Kongsberg SIMRAD EM124 multibeam echosounder system. The CTD measured pressure at of seawater depth was . Due to a technical problem the (unmanned) ultra-deep-sea lander ''Skaff'' used by the Five Deeps Expedition stayed on the bottom for two and half days before it was salvaged by the ''Limiting Factor'' (crew: Patrick Lahey, Pilot; Jonathan Struwe,
DNV GL
DNV (formerly DNV GL) is an international accredited registrar and classification society headquartered in Høvik, Norway. The company currently has about 12,000 employees and 350 offices operating in more than 100 countries, and provides ser ...
Specialist) from an estimated depth of . The gathered data was published with the caveat that it was subject to further analysis and could possibly be revised in the future. The data will be donated to the GEBCO Seabed 2030 initiative. Later in 2019, following a review of bathymetric data, and multiple sensor recordings taken by the DSV ''Limiting Factor'' and the ultra-deep-sea landers ''Closp'', ''Flere'' and ''Skaff'', the Five Deeps Expedition revised the maximum depth to ±.
2020 – ''Ring of Fire Expedition / DSV Limiting Factor''
Caladan Oceanic's "Ring of Fire" expedition in the Pacific included six crewed descents and twenty-five lander deployments into all three basins of the Challenger Deep all piloted by
Victor Vescovo
Victor Lance Vescovo (born 1966) is an American private equity investor, retired naval officer, space tourist and undersea explorer.
He is a co-founder and managing partner of private equity company Insight Equity Holdings. Vescovo achieved the ...
and further topographical and marine life survey of the entire Challenger Deep. The expedition craft used are the Deep Submersible Support Vessel DSSV ''Pressure Drop'', Deep-Submergence Vehicle DSV ''Limiting Factor'' and the ultra-deep-sea landers ''Closp'', ''Flere'' and ''Skaff''.
During the first crewed dive on 7 June 2020 Victor Vescovo and former US astronaut (and former NOAA Administrator) Kathryn D. Sullivan descended to the "Eastern Pool" of the Challenger Deep in the Deep-Submergence Vehicle ''Limiting Factor''.
On 12 June 2020 Victor Vescovo and mountaineer and explorer
Vanessa O'Brien
Vanessa Audi Rhys O'Brien (born 2 December 1964) is a British and American mountaineer, sub-orbital spaceflight participant, explorer, author and former business executive. On 4 August 2022, O'Brien became the first woman to complete the Explore ...
descended to the "Eastern Pool" of the Challenger Deep spending three hours mapping the bottom. O’Brien said her dive scanned about a mile of desolate bottom terrain, finding that the surface is not flat, as once was thought, but sloping, and by about , subject to verification, of course.
On 14 June 2020 Victor Vescovo and John Rost descended to the "Eastern Pool" of the Challenger Deep in the Deep-Submergence Vehicle ''Limiting Factor'' spending four hours at depth and transiting the bottom for nearly 2 miles.
On 20 June 2020 Victor Vescovo and Kelly Walsh descended to the "Western Pool" of the Challenger Deep in the Deep-Submergence Vehicle ''Limiting Factor'' spending four hours at the bottom. They reached a maximum depth of . Kelly Walsh is the son of the '' Trieste’s'' captain
Don Walsh
Don Walsh (born November 2, 1931) is an American oceanographer, explorer and marine policy specialist. He and Jacques Piccard were aboard the bathyscaphe ''Trieste'' when it made a record maximum descent into the Challenger Deep on January 2 ...
who descended there in 1960 with
Jacques Piccard
Jacques Piccard (28 July 19221 November 2008) was a Swiss oceanographer and engineer, known for having developed underwater submarines for studying ocean currents. In the Challenger Deep, he and Lt. Don Walsh of the United States Navy were the ...
.
On 21 June 2020 Victor Vescovo and Woods Hole Oceanographic Institution researcher Ying-Tsong Lin descended to the "Central Pool" of the Challenger Deep in the Deep-Submergence Vehicle ''Limiting Factor''. They reached a maximum depth of ±.
On 26 June 2020 Victor Vescovo and Jim Wigginton descended to the "Eastern Pool" of the Challenger Deep in the Deep-Submergence Vehicle ''Limiting Factor''.
2020 – ''Fendouzhe''
''Fendouzhe'' (奋斗者, ''Striver'') is a crewed
Chinese
Chinese can refer to:
* Something related to China
* Chinese people, people of Chinese nationality, citizenship, and/or ethnicity
**''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation
** List of ethnic groups in China, people of ...
deep-sea submersible developed by the China Ship Scientific Research Center (CSSRC). Between 10 October and 28 November 28, 2020, it carried out thirteen dives in the Mariana Trench as part of a test programme. Of these, eight led to depths of more than . On 10 November 2020, the bottom of the Challenger Deep was reached by ''Fendouzhe'' with three Chinese scientists (Zhāng Wěi 张伟 ilot Zhào Yáng 赵洋, and Wáng Zhìqiáng 王治强) onboard whilst livestreaming the descent to a reported depth of . This makes the '' Fendouzhe '' the fourth crewed submersible vehicle achieving a successful descent. The pressure hull of ''Fendouzhe'', made from a newly developed titanium alloy, offers space for three people in addition to technical equipment. ''Fendouzhe'' is equipped with cameras made by the Norwegian manufacturer Imenco.
According to Ye Cong, the chief designer of the submersible, China's goals for the dive aren't just scientific investigation but also the future use of deep sea seabed resources.
2021 – ''Ring of Fire 2 Expedition / DSV Limiting Factor''
On 28 February 2021 Caladan Oceanic's "Ring of Fire 2" expedition arrived over the Challenger Deep and conducted crewed descents and lander deployments into the Challenger Deep. At the start the (unmanned) ultra-deep-sea lander ''Skaff'' was deployed to collect water column data by CTD for the expedition. The effects of the Pacific subducting plate crashing into the Philippine Plate was amongst the things researched onsite.
On 1 March 2021 the first crewed descent to the eastern pool was made by Victor Vescovo and
Richard Garriott
Richard Allen Garriott de Cayeux (''né'' Garriott; born July 4, 1961) is an American video game developer, entrepreneur and private astronaut. Although both his parents were American, he maintains dual British and American citizenship by birth. ...
. Garriott became the 17th person to descend to the bottom.
On 2 March 2021 a descent to the eastern pool was made by Victor Vescovo and
Michael Dubno
Michael Dubno (born August 23, 1962) is an American inventor, computer scientist, explorer, and video game developer.
Early life and education
Dubno was born in Brooklyn, New York. His family moved to the Bronx where he attended the Bronx ...
.
On 5 March a descent to the eastern pool was made by Victor Vescovo and
Hamish Harding
Hamish Harding is a UAE-based British businessman, aviator, explorer, and space tourist. He is the founder of Action Group and chairman of Action Aviation, an international aircraft brokerage company with headquarters in Dubai, United Arab Emira ...
. They traversed the bottom of Challenger Deep.
On 11 March 2021 a descent to the western pool was made by Victor Vescovo and marine botanist
Nicole Yamase
Nicole may refer to:
People
* Nicole (name)
* Nicole (American singer) (born 1958), a contestant in season 3 of the American ''The X Factor''
* Nicole (Chilean singer) (born 1977)
* Nicole (German singer) (born 1964), winner of the 1982 Eurovi ...
.
On 13 April 2021 a descent was made by deep water submersible operations expert Rob McCallum and Tim Macdonald who piloted the dive.
A 2021 descent with a Japanese citizen is planned.
All crewed descents were conducted in the Deep-Submergence Vehicle ''
DSV Limiting Factor
A deep-submergence vehicle (DSV) is a deep-diving crewed submersible that is self-propelled. Several navies operate vehicles that can be accurately described as DSVs. DSVs are commonly divided into two types: research DSVs, which are used for ex ...
''.
2022 - ''Ring of Fire 3 Expedition / DSV Limiting Factor''
In July 2022 for the fourth consecutive year, Caladan Oceanic's deep submergence system, consisting of the deep submersible DSV ''Limiting Factor'' supported by the mother ship DSSV ''Pressure Drop'', returned to the Challenger Deep for dives into the Challenger Deep.
In early July, 2022 Victor Vescovo was joined by Aaron Newman as mission specialist for a dive into the Central pool. On July 5, 2022 Tim Macdonald as pilot and Jim Kitchen as mission specialist for a dive into the Eastern pool. On July 8, 2022 Victor Vescovo was joined by Dylan Taylor as mission specialist for a dive into the Eastern pool.
Victor Vescovo (for his 15th dive into the Challenger Deep) was joined by geographer and oceanographer
Dawn Wright
Dawn Jeannine Wright (born April 15, 1961) is an American geographer and oceanographer. She is a leading authority in the application of geographic information system (GIS) technology to the field of ocean and coastal science, and played a key ro ...
as mission specialist on the July 12, 2022 dive to in the Western pool. Wright operated the world's first sidescan sonar to ever operate at full-ocean depth to capture detailed imagery along short transects of the southern wall of the Western pool.
Uncrewed descents by ROVs
1996 and 1998 – ''Kaikō''
The remotely operated vehicle (ROV) ''Kaikō'' made many unmanned descents to the Mariana Trench from its support ship RV ''Yokosuka'' during two expeditions in 1996 and 1998.
From 29 February to 4 March the ROV ''Kaiko'' made three dives into the ''central'' basin, ''Kaiko'' #21 – ''Kaiko'' #23, . Depths ranged from at , to at ; dives #22 & #23 to the north, and dive #21 northeast of the deepest waters of the ''central'' basin. During the 1996 measurements the temperature (water temperature increases at great depth due to adiabatic compression),
salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
and water pressure at the sampling station was , 34.7‰ and , respectively at depth. The Japanese robotic deep-sea probe ''Kaikō'' broke the depth record for unmanned probes when it reached close to the surveyed bottom of the Challenger Deep. Created by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), it was one of the few unmanned deep-sea probes in operation that could dive deeper than . The manometer measured depth of ± at for the Challenger Deep is believed to be the most accurate measurement taken up to then.
Another source states the greatest depth measured by ''Kaikō'' in 1996 was at and at in 1998.
The ROV ''Kaiko'' was the first vehicle to visit to the bottom of the Challenger Deep since the bathyscaph ''Triestes dive in 1960, and the first success in sampling the trench bottom sediment/mud, from which ''Kaiko'' obtained over 360 samples. Approximately 3,000 different microbes were identified in the samples."Life Is Found Thriving at Ocean's Deepest Point" National Geographic News, 3 February 2005
''Kaikō'' was lost at sea off
Shikoku Island
is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), '' ...
From 2 May to 5 June 2009, the RV ''Kilo Moana'' hosted the
Woods Hole Oceanographic Institution
The Woods Hole Oceanographic Institution (WHOI, acronym pronounced ) is a private, nonprofit research and higher education facility dedicated to the study of marine science and engineering.
Established in 1930 in Woods Hole, Massachusetts, it i ...
Nereus
In Greek mythology, Nereus ( ; ) was the eldest son of Pontus (the Sea) and Gaia ( the Earth), with Pontus himself being a son of Gaia. Nereus and Doris became the parents of 50 daughters (the Nereids) and a son ( Nerites), with whom Nereus ...
'' team for the first operational test of the ' in its 3-ton tethered ROV mode. The ''Nereus'' team was headed by the Expedition Leader Andy Bowen of WHOI, Dr. Louis Whitcomb of
Johns Hopkins University
Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hem ...
, and Dr. Dana Yoerger, also of WHOI. The expedition had co-chief scientists: biologist Dr. Tim Shank of WHOI, and geologist Dr. Patricia Fryer of the University of Hawaii, to head the science team exploiting the ship’s
bathymetry
Bathymetry (; ) is the study of underwater depth of ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water de ...
and organizing the science experiments deployed by the ''Nereus''. From ''Nereus'' dive #007ROV to just south of Guam, to dive #010ROV into the Nero Deep at , the testing gradually increased depths and complexities of activities at the bottom.
Dive #011ROV, on 31 May 2009, saw the ''Nereus'' piloted on a 27.8-hour underwater mission, with about ten hours transversing the ''eastern'' basin of the Challenger Deep – from the south wall, northwest to the north wall – streaming live video and data back to its mothership. A maximum depth of was registered at . The ' then relocated to the ''western'' basin, where a 19.3-hour underwater dive found a maximum depth of on dive #012ROV, and on dive #014ROV in the same area (11°19.59 N, 142°12.99 E) encountered a maximum depth of . The ''Nereus'' was successful in recovering both sediment and rock samples from the ''eastern'' and the ''western'' basins with its manipulator arm for further scientific analysis. The HROV’s final dive was about to the north of the Challenger Deep, in the
backarc
The back-arc region is the area behind a volcanic arc. In island volcanic arcs, it consists of back-arc basins of oceanic crust with abyssal depths, which may be separated by remnant arcs, similar to island arcs. In continental arcs, the back- ...
, where they dove at the TOTO Caldera (12°42.00 N, 143°31.5 E). Nereus thus became the first vehicle to reach the Mariana Trench since 1998 and the deepest-diving vehicle then in operation. Project manager and developer Andy Bowen heralded the achievement as "the start of a new era in ocean exploration". ''Nereus'', unlike ''Kaikō'', did not need to be powered or controlled by a cable connected to a ship on the ocean surface.
The HROV ''Nereus'' was lost on 10 May 2014 while conducting a dive at in depth in the
Kermadec Trench
The Kermadec Trench is a linear ocean trench in the south Pacific Ocean. It stretches about from the Louisville Seamount Chain in the north (26°S) to the Hikurangi Plateau in the south (37°S), north-east of New Zealand's North Island. Toget ...
.
Uncrewed descents near the Challenger Deep
2008 – ''ABISMO''
In June 2008, the
Japan Agency for Marine-Earth Science and Technology
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
(JAMSTEC) deployed the research vessel ''Kairei'' to the area of
Guam
Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
for cruise KR08-05 Leg 1 and Leg 2.
On 1–3 June 2008, during Leg 1, the Japanese robotic deep-sea probe ''
ABISMO
''ABISMO'' (Automatic Bottom Inspection and Sampling Mobile) is a remotely operated underwater vehicle (ROV) built by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) for exploration of the deep sea. It is the only remaining ROV ...
'' (Automatic Bottom Inspection and Sampling Mobile) on dives 11–13 almost reached the bottom about east of the Challenger Deep: "Unfortunately, we were unable to dive to the sea floor because the legacy primary cable of the Kaiko system was a little bit short. The 2-m long gravity core sampler was dropped in free fall, and sediment samples of 1.6m length were obtained. Twelve bottles of water samples were also obtained at various depths..." ABISMO's dive #14 was into the TOTO caldera (12°42.7777 N, 143°32.4055 E), about 60 nmi northeast of the deepest waters of the ''central'' basin of the Challenger Deep, where they obtained videos of the hydrothermal plume. Upon successful testing to , JAMSTEC' ROV ''ABISMO'' became, briefly, the only full-ocean-depth rated ROV in existence. On 31 May 2009, the ABISMO was joined by the Woods Hole Oceanographic Institution's HROV ''Nereus'' as the only two operational full ocean depth capable
remotely operated vehicle
A remotely operated underwater vehicle (technically ROUV or just ROV) is a tethered underwater mobile device, commonly called ''underwater robot''.
Definition
This meaning is different from remote control vehicles operating on land or in the ai ...
s in existence. During the ROV ''ABISMO's'' deepest sea trails dive its
manometer
Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressur ...
measured a depth of ± in "Area 1" (vicinity of 12°43' N, 143°33' E).
Leg 2, under chief scientist Takashi Murashima, operated at the Challenger Deep 8–9 June 2008, testing JAMSTEC’s new full ocean depth "Free Fall Mooring System," i.e. a lander. The lander was successfully tested twice to depth, taking video images and sediment samplings at , in the ''central'' basin of the Challenger Deep.
2016 – ''Haidou-1''
On 23 May 2016, the Chinese submersible ''Haidou-1'' dove to a depth of at an undisclosed position in the Mariana Trench, making China the third country after Japan (ROV ''Kaikō''), and the US (HROV ''Nereus''), to deploy a full-ocean-depth ROV. This autonomous and remotely operated vehicle has a design depth of .
2020 – ''Vityaz-D''
On 8 May 2020, the Russian submersible ''Vityaz-D'' dove to a depth of at an undisclosed position in the Mariana Trench.
Lifeforms
The summary report of the expedition lists
radiolaria
The Radiolaria, also called Radiozoa, are protozoa of diameter 0.1–0.2 mm that produce intricate mineral skeletons, typically with a central capsule dividing the cell (biology), cell into the inner and outer portions of endoplasm and Ecto ...
from the two dredged samples taken when the Challenger Deep was first discovered. These (''
Nassellaria
Nassellaria is an order of Rhizaria belonging to the class Radiolaria. The organisms of this order are characterized by a skeleton cross link with a cone or ring.
Introduction
Nassellaria is an order of Radiolaria under the class Polycystina. ...
'' and ''
Spumellaria
Spumellaria is an order of radiolarians in the class Polycystinea. They are ameboid protists appearing in abundance in the world's oceans, possessing a radially-symmetrical silica (opal) skeleton that has ensured their preservation in fossil rec ...
'') were reported in the Report on Radiolaria (1887) written by
Ernst Haeckel
Ernst Heinrich Philipp August Haeckel (; 16 February 1834 – 9 August 1919) was a German zoologist, naturalist, eugenicist, philosopher, physician, professor, marine biologist and artist. He discovered, described and named thousands of new sp ...
.
On their 1960 descent, the crew of the ''Trieste'' noted that the floor consisted of
diatom
A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...
aceous ooze and reported observing "some type of flatfish" lying on the seabed.
Many marine biologists are now skeptical of this supposed sighting, and it is suggested that the creature may instead have been a
sea cucumber
Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuria ...
. The video camera on board the ''Kaiko'' probe spotted a sea cucumber, a scale worm and a
shrimp
Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...
at the bottom. At the bottom of the Challenger deep, the ''Nereus'' probe spotted one
polychaete
Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that ...
worm (a multi-legged predator) about an inch long.
An analysis of the sediment samples collected by ''Kaiko'' found large numbers of simple organisms at . While similar lifeforms have been known to exist in shallower ocean trenches (> 7,000 m) and on the
abyssal plain
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between and . Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. T ...
, the lifeforms discovered in the Challenger Deep possibly represent
taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
distinct from those in shallower ecosystems.
Most of the organisms collected were simple, soft-shelled
foraminifera
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and ot ...
(432 species according to National Geographic), with four of the others representing species of the complex, multi-chambered genera '' Leptohalysis'' and '' Reophax''. Eighty-five percent of the specimens were organic, soft-shelled
allogromiid
The Allogromiida is an order of single-chambered, mostly organic-walled foraminiferans, including some that produce agglutinated tests (Lagynacea). Genetic studies indicate that some foraminiferans with agglutinated tests, previously included in ...
s, which is unusual compared to samples of sediment-dwelling organisms from other deep-sea environments, where the percentage of organic-walled foraminifera ranges from 5% to 20%. As small organisms with hard, calcareous shells have trouble growing at extreme depths because of the high solubility of calcium carbonate in the pressurized water, scientists theorize that the preponderance of soft-shelled organisms in the Challenger Deep may have resulted from the typical
biosphere
The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also be ...
present when the Challenger Deep was shallower than it is now. Over the course of six to nine million years, as the Challenger Deep grew to its present depth, many of the species present in the sediment died out or were unable to adapt to the increasing water pressure and changing environment.
On 17 March 2013, researchers reported data that suggested piezophilic microorganisms thrive in the Challenger Deep. Other researchers reported related studies that microbes thrive inside rocks up to below the sea floor under of ocean off the coast of the northwestern United States. According to one of the researchers, "You can find microbes everywherethey're extremely adaptable to conditions, and survive wherever they are."
See also
*
Emden Deep
The Emden Deep, also known as the Galathea Deep or Galathea Depth, is the portion of the Philippine Trench exceeding depths in the south-western Pacific Ocean.
Originally discovered by the German ship ''Emden'' in 1927, it was first explored ...
List of people who descended to Challenger Deep
The Challenger Deep (CD) is the deepest known point in the Earth's seabed hydrosphere, a slot-shaped valley in the floor of Mariana Trench, with depths exceeding 10,900 meters. It is located in the Federated States of Micronesia. In 2019, sonar ma ...
*
Sirena Deep
The Sirena Deep, originally named the HMRG Deep, was discovered in 1997 by a team of scientists from Hawaii. Its directly measured depth of is third only to the Challenger Deep and Horizon Deep, currently the deepest known directly measured ...