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A swimming pool, swimming bath, wading pool, paddling pool, or simply pool, is a structure designed to hold water to enable
swimming Swimming is the self-propulsion of a person through water, or other liquid, usually for recreation, sport, exercise, or survival. Locomotion is achieved through coordinated movement of the limbs and the body to achieve hydrodynamic thrust that r ...
or other leisure activities. Pools can be built into the ground (in-ground pools) or built above ground (as a freestanding construction or as part of a building or other larger structure), and may be found as a feature aboard ocean-liners and cruise ships. In-ground pools are most commonly constructed from materials such as
concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
, natural stone, metal, plastic, or
fiberglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
, and can be of a custom size and shape or built to a standardized size, the largest of which is the
Olympic-size swimming pool An Olympic-size swimming pool conforms to regulated dimensions that are large enough for international competition. This type of swimming pool is used in the Olympic Games, where the race course is in length, typically referred to as "long cour ...
. Many
health club A health club (also known as a fitness club, fitness center, health spa, and commonly referred to as a gym) is a place that houses exercise equipment for the purpose of physical exercise. In recent years, the number of fitness and health se ...
s,
fitness center A health club (also known as a fitness club, fitness center, health spa, and commonly referred to as a gym) is a place that houses exercise equipment for the purpose of physical exercise. In recent years, the number of fitness and health ser ...
s, and private clubs have pools used mostly for exercise or recreation. It is common for municipalities of every size to provide pools for public use. Many of these municipal pools are outdoor pools but indoor pools can also be found in buildings such as
natatorium A swimming pool, swimming bath, wading pool, paddling pool, or simply pool, is a structure designed to hold water to enable Human swimming, swimming or other leisure activities. Pools can be built into the ground (in-ground pools) or built ...
s and
leisure center A leisure centre in the United Kingdom, Ireland, Australia (also called aquatic centres), Singapore and Canada is a purpose-built building or site, usually owned and operated by the city, borough council or municipal district council, where people ...
s. Hotels may have pools available for their guests to use at their own leisure. Pools as a feature in hotels are more common in tourist areas or near
convention center A convention center (American English; or conference centre in British English) is a large building that is designed to hold a convention, where individuals and groups gather to promote and share common interests. Convention centers typica ...
s. Educational facilities such as high schools and universities sometimes have pools for physical education classes, recreational activities, leisure, and competitive athletics such as swimming teams. Hot tubs and
spa A spa is a location where mineral-rich spring water (and sometimes seawater) is used to give medicinal baths. Spa towns or spa resorts (including hot springs resorts) typically offer various health treatments, which are also known as balneoth ...
s are pools filled with water that is heated and then used for relaxation or
hydrotherapy Hydrotherapy, formerly called hydropathy and also called water cure, is a branch of alternative medicine (particularly naturopathy), occupational therapy, and physiotherapy, that involves the use of water for pain relief and treatment. The term ...
. Specially designed swimming pools are also used for
diving Diving most often refers to: * Diving (sport), the sport of jumping into deep water * Underwater diving, human activity underwater for recreational or occupational purposes Diving or Dive may also refer to: Sports * Dive (American football), a ...
, water sports, and
physical therapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, patient ...
, as well as for the training of
lifeguard A lifeguard is a rescuer who supervises the safety and rescue of swimmers, surfers, and other water sports participants such as in a swimming pool, water park, beach, spa, river and lake. Lifeguards are trained in swimming and CPR/ AED first a ...
s and
astronaut An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
s. Swimming pools most commonly use chlorinated water or salt water and may be heated or unheated.


History


Pre-modern

The "
Great Bath The Great Bath is one of the best-known structures among the ruins of the Harappan Civilization excavated at Mohenjo-daro in Sindh, Pakistan.
" at the site of
Mohenjo-Daro Mohenjo-daro (; sd, موئن جو دڙو'', ''meaning 'Mound of the Dead Men';Ancient Greeks Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cultu ...
and
Romans Roman or Romans most often refers to: *Rome, the capital city of Italy * Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a lette ...
built artificial pools for athletic training in the
palaestra A palaestra ( or ; also (chiefly British) palestra; grc-gre, παλαίστρα) was any site of an ancient Greek wrestling school. Events requiring little space, such as boxing and wrestling, took place there. Palaestrae functioned both indep ...
s, for nautical games and for military exercises. Roman emperors had private swimming pools in which fish were also kept, hence one of the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
words for a pool was ''piscina''. The first heated swimming pool was built by
Gaius Maecenas Gaius Cilnius Maecenas ( – 8 BC) was a friend and political advisor to Octavian (who later reigned as emperor Augustus). He was also an important patron for the new generation of Augustan poets, including both Horace and Virgil. During the rei ...
in his gardens on the
Esquiline Hill The Esquiline Hill (; la, Collis Esquilinus; it, Esquilino ) is one of the Seven Hills of Rome. Its southernmost cusp is the ''Oppius'' ( Oppian Hill). Etymology The origin of the name ''Esquiline'' is still under much debate. One view is ...
of
Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus (legendary) , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg , map_caption ...
, likely sometime between 38 and 8 BC. Gaius Maecenas was a wealthy imperial advisor to
Augustus Caesar Augustus (born Gaius Octavius; 23 September 63 BC – 19 August AD 14), also known as Octavian, was the first Roman emperor; he reigned from 27 BC until his death in AD 14. He is known for being the founder of the Roman Pri ...
and considered one of the first patrons of arts. Ancient
Sinhalese Sinhala may refer to: * Something of or related to the Sinhalese people of Sri Lanka * Sinhalese people * Sinhala language, one of the three official languages used in Sri Lanka * Sinhala script, a writing system for the Sinhala language ** Sinha ...
built a pair of pools called "
Kuttam Pokuna Kuttam Pokuna (twin ponds or pools) are well preserved old bathing tanks or ponds in Sri Lanka. This pair of ponds was built by the Sinhalese in the ancient Anuradhapura Kingdom. They form part of the Abhayagiri vihāra complex and are an example o ...
" in the kingdom of
Anuradhapura Anuradhapura ( si, අනුරාධපුරය, translit=Anurādhapuraya; ta, அனுராதபுரம், translit=Aṉurātapuram) is a major city located in north central plain of Sri Lanka. It is the capital city of North Central ...
, Sri Lanka, in the 6th century AD. They were decorated with flights of steps, punkalas or pots of abundance, and scroll design.Kuttam Pokuna
by Lanka Pradeepa, 3 November 2020, retrieved 8 July 2022.


19th century

Swimming pools became popular in Britain in the mid-19th century. As early as 1837, six indoor pools with diving boards existed in London, England. The Maidstone Swimming Club in
Maidstone Maidstone is the largest Town status in the United Kingdom, town in Kent, England, of which it is the county town. Maidstone is historically important and lies 32 miles (51 km) east-south-east of London. The River Medway runs through the c ...
,
Kent Kent is a county in South East England and one of the home counties. It borders Greater London to the north-west, Surrey to the west and East Sussex to the south-west, and Essex to the north across the estuary of the River Thames; it faces ...
is believed to be the oldest surviving swimming club in Britain. It was formed in 1844, in response to concerns over drownings in the
River Medway The River Medway is a river in South East England. It rises in the High Weald AONB, High Weald, East Sussex and flows through Tonbridge, Maidstone and the Medway conurbation in Kent, before emptying into the Thames Estuary near Sheerness, a to ...
, especially since would-be rescuers would often drown because they themselves could not swim to safety. The club used to swim in the River Medway, and would hold races, diving competitions and
water polo Water polo is a competitive team sport played in water between two teams of seven players each. The game consists of four quarters in which the teams attempt to score goals by throwing the ball into the opposing team's goal. The team with the ...
matches. ''The South East Gazette'' July 1844 reported an aquatic breakfast party: coffee and biscuits were served on a floating raft in the river. The coffee was kept hot over a fire; club members had to tread water and drink coffee at the same time. The last swimmers managed to overturn the raft, to the amusement of 150 spectators. The
Amateur Swimming Association Swim England is the national governing body for swimming, diving, water polo, open water swimming, and synchronised swimming in England. It forms part of British Swimming, a federation of the national governing bodies of England, Scotland ( Scott ...
was founded in 1869 in England, and the Oxford Swimming Club in 1909. The presence of indoor baths in the cobbled area of
Merton Street Merton Street is a historic and picturesque cobbled street in central Oxford, England. ...
might have persuaded the less hardy of the aquatic brigade to join. So, bathers gradually became swimmers, and bathing pools became swimming pools. In 1939,
Oxford Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...
created its first major public indoor pool at Temple Cowley. The modern
Olympic Games The modern Olympic Games or Olympics (french: link=no, Jeux olympiques) are the leading international sporting events featuring summer and winter sports competitions in which thousands of athletes from around the world participate in a var ...
started in 1896 and included swimming races, after which the popularity of swimming pools began to spread. In the US, the
Racquet Club of Philadelphia The Racquet Club of Philadelphia (RCOP) is a private social club and athletic club in Philadelphia, Pennsylvania. It has facilities for squash, real tennis, and racquets. The club is ranked in the Top 20 Athletic Clubs on the Platinum Club of A ...
clubhouse (1907) boasts one of the world's first modern above-ground swimming pools. The first swimming pool to go to sea on an ocean liner was installed on the
White Star Line The White Star Line was a British shipping company. Founded out of the remains of a defunct packet company, it gradually rose up to become one of the most prominent shipping lines in the world, providing passenger and cargo services between t ...
's ''Adriatic'' in 1906. The oldest known public swimming pool in the U.S., Underwood Pool, is located in
Belmont, Massachusetts Belmont is a town in Middlesex County, Massachusetts. It is a western suburb of Boston, Massachusetts, United States; and is part of the Greater Boston metropolitan area. At the time of the 2020 U.S. Census, the town's population stood at 27,295 ...
. Interest in competitive swimming grew following
World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
. Standards improved and training became essential. Home swimming pools became popular in the United States after
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
and the publicity given to swimming sports by Hollywood films such as
Esther Williams Esther Jane Williams (August 8, 1921 – June 6, 2013) was an American competitive swimmer and actress. She set regional and national records in her late teens on the Los Angeles Athletic Club swim team. Unable to compete in the 1940 Summer Ol ...
' ''
Million Dollar Mermaid ''Million Dollar Mermaid'' (also known as ''The One Piece Bathing Suit'' in the UK) is a 1952 Metro-Goldwyn-Mayer biographical film of the life of Australian swimming star Annette Kellerman. It was directed by Mervyn LeRoy and produced by Arthur ...
'' made a home pool a desirable status symbol. More than 50 years later, the home or residential swimming pool is a common sight. Some small nations enjoy a thriving swimming pool industry (e.g., New Zealand pop. 4,116,900 – holds the record in pools per capita with 65,000 home swimming pools and 125,000 spa pools). A two-storey, white concrete swimming pool building composed of horizontal cubic volumes built in 1959 at the
Royal Roads Military College Royal Roads Military College (RRMC) was a Canadian military college from 1940 to 1995, located in Hatley Park, Colwood, British Columbia, near Victoria, British Columbia, Canada. The facility now serves as the campus of Royal Roads University, a ...
is on the Registry of Historic Places of Canada.


World records

According to the
Guinness World Records ''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a reference book published annually, listing world ...
, the largest swimming pool in the world is
San Alfonso del Mar San Alfonso del Mar, sometimes spelled "San Alphonso del Mar", is a private resort in Algarrobo, Chile, about west of Santiago. Facilities * 1,200 second home units. * Sub-Acqua Café Aquarium, located on the edge of the artificial lagoon. * ...
Seawater pool in Algarrobo,
Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
. It is long and has an area of 8 ha (20 acres). At its deepest, it is deep. It was completed in December 2006. The largest indoor
wave pool A wave pool is a swimming pool in which there are artificially generated, large waves, similar to those of the ocean. Wave pools are often a major feature of water parks, both indoors and outdoors, as well as some leisure centres. History T ...
in the world is at
DreamWorks Water Park DreamWorks Water Park is an indoor water park within the American Dream shopping and entertainment complex, at the Meadowlands Sports Complex in East Rutherford, New Jersey, United States. The park opened on October 1, 2020. The water park incl ...
within the American Dream shopping and entertainment complex at the
Meadowlands Sports Complex The Meadowlands Sports Complex is a sports complex located in East Rutherford, in Bergen County, New Jersey, United States. The facility is owned and operated by the New Jersey Sports and Exposition Authority (NJSEA). The complex currently consi ...
in
East Rutherford, New Jersey East Rutherford is a borough in Bergen County, New Jersey, United States. As of the 2020 U.S. census, the borough's population was 10,022, reflecting an increase of 1,109 (+12.4%) from the 8,913 counted in the 2010 census.
, United States, and the largest indoor pool in North America is at the
Neutral Buoyancy Lab The Neutral Buoyancy Laboratory (NBL) is an astronaut training facility and neutral buoyancy pool operated by NASA and located at the Sonny Carter Training Facility, near the Johnson Space Center in Houston, Texas. The NBL's main feature is a la ...
in the
Sonny Carter Training Facility The Neutral Buoyancy Laboratory (NBL) is an astronaut training facility and neutral buoyancy pool operated by NASA and located at the Sonny Carter Training Facility, near the Johnson Space Center in Houston, Texas. The NBL's main feature is a l ...
at
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
JSC in Houston. In 2021,
Deep Dive Dubai Deep Dive Dubai is a deep diving pool in Dubai Dubai (, ; ar, دبي, translit=Dubayy, , ) is the most populous city in the United Arab Emirates (UAE) and the capital of the Emirate of Dubai, the most populated of the 7 emirates of the Un ...
, located in Dubai, UAE, was certified by the
Guinness Book of World Records ''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a reference book published annually, listing world ...
as the world's deepest swimming pool reaching . The
Y-40 Hotel Terme Millepini is a four-star hotel in Montegrotto Terme, Padua, Italy. It contains 100 rooms and until 2020 was recognized for having the world's deepest pool, the Y-40, which put it in the Guinness World Records. The hotel was first built ...
swimming pool at the
Hotel Terme Millepini Hotel Terme Millepini is a four-star hotel in Montegrotto Terme, Padua, Italy. It contains 100 rooms and until 2020 was recognized for having the world's deepest pool, the Y-40, which put it in the Guinness World Records. The hotel was first built ...
in
Padua Padua ( ; it, Padova ; vec, Pàdova) is a city and ''comune'' in Veneto, northern Italy. Padua is on the river Bacchiglione, west of Venice. It is the capital of the province of Padua. It is also the economic and communications hub of the ...
, Italy, previously held the record, , from 2014 until 2021. The
Fleishhacker Pool Fleishhacker Pool was a public saltwater swimming pool complex, located in the southwest corner of San Francisco, California, United States, next to the San Francisco Zoo at Sloat Boulevard and the Great Highway. Upon its completion in 1925, it w ...
in San Francisco was the largest heated outdoor swimming pool in the United States. Opened on 23 April 1925, it measured and was so large that the lifeguards required
kayak A kayak is a small, narrow watercraft which is typically propelled by means of a double-bladed paddle. The word kayak originates from the Greenlandic word ''qajaq'' (). The traditional kayak has a covered deck and one or more cockpits, each se ...
s for patrol. It was closed in 1971 due to low patronage. In Europe, the largest swimming pool opened in 1934 in
Elbląg Elbląg (; german: Elbing, Old Prussian: ''Elbings'') is a city in the Warmian-Masurian Voivodeship, Poland, located in the eastern edge of the Żuławy region with 117,390 inhabitants, as of December 2021. It is the capital of Elbląg County. ...
(
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...
), providing a water area of . One of the largest swimming pools ever built was reputedly created in
Moscow Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...
after the
Palace of Soviets The Palace of the Soviets (russian: Дворец Советов, ''Dvorets Sovetov'') was a project to construct a political convention center in Moscow on the site of the demolished Cathedral of Christ the Saviour. The main function of the p ...
remained uncompleted. The foundations of the palace were converted into the
Moskva Pool The Moskva Pool (Moscow Pool) was, for a time, the world's largest open air swimming pool. It was built in Moscow in 1958 on the foundation of the abandoned Palace of the Soviets, to the designs of Moscow architect Dmitry Chechulin. Constructio ...
open-air swimming pool after the process of
de-Stalinisation De-Stalinization (russian: десталинизация, translit=destalinizatsiya) comprised a series of political reforms in the Soviet Union after the death of long-time leader Joseph Stalin in 1953, and the thaw brought about by ascension ...
. However, after the fall of
communism Communism (from Latin la, communis, lit=common, universal, label=none) is a far-left sociopolitical, philosophical, and economic ideology and current within the socialist movement whose goal is the establishment of a communist society, a s ...
,
Christ the Saviour Cathedral The Cathedral of Christ the Saviour ( rus, Храм Христа́ Спаси́теля, r=Khram Khristá Spasítelya, p=xram xrʲɪˈsta spɐˈsʲitʲɪlʲə) is a Russian Orthodox cathedral in Moscow Moscow ( , US chiefly ; rus, link ...
was re-built on the site between 1995 and 2000; the cathedral had originally been located there. The highest swimming pool is believed to be in
Yangbajain Yangbajain (also spelled Yangbajing; ) is a town approximately north-west of Lhasa, halfway to Damxung in the Tibet Autonomous Region of China. The town lies just south of the Nyainqêntanglha Mountains, in an upland lush green valley surrounde ...
(Tibet, China). This resort is located at AMSL and has two indoor swimming pools and one outdoor swimming pool, all filled with water from
hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circ ...
s.


Dimensions

:''See: Competition pools (below)'' Length: Most pools in the world are measured in metres, but in the United States pools are often measured in feet and yards. In the UK most pools are calibrated in metres, but older pools measured in yards still exist. In the US, pools tend to either be 25 yards (SCY-
short course In swimming, the term short course (abbreviated SC) is used to identify a pool that is in length. The term is also often included in meet names when conducted in a short course pool. "Short course" is the second type of pool configuration current ...
yards), 25 metres (SCM-short course metres) or 50 metres (
long course An Olympic-size swimming pool conforms to regulated dimensions that are large enough for international competition. This type of swimming pool is used in the Olympic Games, where the race course is in length, typically referred to as "long cour ...
). US high schools and the
NCAA The National Collegiate Athletic Association (NCAA) is a nonprofit organization that regulates student athletics among about 1,100 schools in the United States, Canada, and Puerto Rico. It also organizes the athletic programs of colleges an ...
conduct short course (25 yards) competition. There are also many pools  m long, so that 3 lengths = 100 m. This pool dimension is commonly used to accommodate water polo.
USA Swimming USA Swimming is the national governing body for competitive swimming in the United States. It is charged with selecting the United States Olympic Swimming team and any other teams that officially represent the United States, as well as the overal ...
(USA-S) swims in both metric and non-metric pools. However, the international standard is metres, and world records are only recognized when swum in 50 m pools (or 25 m for short course) but 25-yard pools are very common in the US. In general, the shorter the pool, the faster the time for the same distance, since the swimmer gains speed from pushing off the wall after each turn at the end of the pool. Width: Most European pools are between 10 m and 50 m wide. Depth: The depth of a swimming pool depends on the purpose of the pool, and whether it is open to the public or strictly for private use. If it is a private casual, relaxing pool, it may go from deep. If it is a public pool designed for diving, it may slope from in the deep end. A children's play pool may be from deep. Most public pools have differing depths to accommodate different swimmer requirements. In many jurisdictions, it is a requirement to show the water depth with clearly marked depths affixed to the pool walls.


Types

Pools can be either indoors or outdoors. They can be of any size and shape, and inground or above ground. Most pools are permanent fixtures, while others are temporary, collapsible structures.


Private pools

Private pools are usually smaller than public pools, on average to whereas public pools usually start at . Home pools can be permanently built-in, or be assembled above ground and disassembled after summer. Privately owned outdoor pools in backyards or gardens started to proliferate in the 1950s in regions with warm summer climates, particularly in the United States with
desegregation Desegregation is the process of ending the separation of two groups, usually referring to races. Desegregation is typically measured by the index of dissimilarity, allowing researchers to determine whether desegregation efforts are having impact o ...
. A ''plunge pool'' is a smaller, permanently installed swimming pool, with a maximum size of approximately . Construction methods for private pools vary greatly. The main types of in-ground pools are gunite
shotcrete Shotcrete, gunite (), or sprayed concrete is concrete or mortar conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique, first used in 1907 invented by Carl Akeley. It is typically r ...
, concrete,
vinyl Vinyl may refer to: Chemistry * Polyvinyl chloride (PVC), a particular vinyl polymer * Vinyl cation, a type of carbocation * Vinyl group, a broad class of organic molecules in chemistry * Vinyl polymer, a group of polymers derived from vinyl m ...
-lined, and one-piece fiberglass shells. Many countries now have strict pool fencing requirements for private swimming pools, which require pool areas to be isolated so that unauthorized children younger than six years cannot enter. Many countries require a similar level of protection for the children residing in or visiting the house, although many pool owners prefer the visual aspect of the pool in close proximity to their living areas, and will not provide this level of protection. There is no consensus between states or countries on the requirements to fence private swimming pools, and in many places they are not required at all, particularly in rural settings.


Children's pools

Inexpensive temporary polyvinyl chloride pools can be bought in supermarkets and taken down after summer. They are used mostly outdoors in yards, are typically shallow, and often their sides are inflated with air to stay rigid. When finished, the water and air can be let out and this type of pool can be folded up for convenient storage. They are regarded in the swimming pool industry as "splasher" pools intended for cooling off and amusing toddlers and children, not for swimming, hence the alternate name of "kiddie" pools.
Toy A toy or plaything is an object that is used primarily to provide entertainment. Simple examples include toy blocks, board games, and dolls. Toys are often designed for use by children, although many are designed specifically for adults and pet ...
s are available for children and other people to play with in pool water. They are often blown up with air so they are soft but still reasonably rugged, and can float in water. File:Black Labrador Retriever kiddie pool..jpg, A black labrador retriever bathing in a kiddie pool File:Kids.jpg, Children playing in an inflatable pool


Public pools

Public pools are often part of a larger
leisure center A leisure centre in the United Kingdom, Ireland, Australia (also called aquatic centres), Singapore and Canada is a purpose-built building or site, usually owned and operated by the city, borough council or municipal district council, where people ...
or recreational complex. These centres often have more than one pool, such as an indoor heated pool, an outdoor (
chlorinated In chemistry, halogenation is a chemical reaction that entails the introduction of one or more halogens into a compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers, ...
,
saltwater Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, ...
or
ozonated Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic Allotropy, allotrope , breaking down i ...
) pool which may be heated or unheated, a shallower children's pool, and a paddling pool for toddlers and infants. There may also be a
sauna A sauna (, ), or sudatory, is a small room or building designed as a place to experience dry or wet heat sessions, or an establishment with one or more of these facilities. The steam and high heat make the bathers perspire. A thermometer in a ...
and one or more hot tubs or
spa A spa is a location where mineral-rich spring water (and sometimes seawater) is used to give medicinal baths. Spa towns or spa resorts (including hot springs resorts) typically offer various health treatments, which are also known as balneoth ...
pools ("
jacuzzi Jacuzzi Brands LLC (; ), through its subsidiaries, is a global manufacturer and distributor of branded baths, hot tubs, pools, saunas and, formerly, aircraft. Founded in 1915 by the Italian family of the same name, Jacuzzi is a federally regist ...
s"). Many upscale hotels and holiday resorts have a swimming pool for use by their guests. If a pool is in a separate building, the building may be called a
natatorium A swimming pool, swimming bath, wading pool, paddling pool, or simply pool, is a structure designed to hold water to enable Human swimming, swimming or other leisure activities. Pools can be built into the ground (in-ground pools) or built ...
. The building may sometimes also have facilities for related activities, such as a diving tank. Larger pools sometimes have a diving board affixed at one edge above the water. Many public swimming pools are
rectangle In Euclidean plane geometry, a rectangle is a quadrilateral with four right angles. It can also be defined as: an equiangular quadrilateral, since equiangular means that all of its angles are equal (360°/4 = 90°); or a parallelogram containi ...
s 25 m or 50 m long, but they can be any size and shape. There are also elaborate pools with
artificial waterfall An artificial waterfall is a water feature or fountain which imitates a natural waterfall. Artificial waterfalls have long been featured in traditional Japanese gardens, where they can serve to highlight a scene or to provide focus. The classic ...
s, fountains,
splash pad A splash pad or spray pool is a recreation area, often in a public park, for water play that has little or no standing water. This is said to eliminate the need for lifeguards or other supervision, as there is little risk of drowning. Typicall ...
s, wave machines, varying depths of water, bridges, and island bars. Some swimming facilities have
locker A locker is a small, usually narrow storage compartment. They are commonly found in dedicated cabinets, very often in large numbers, in various public places such as locker rooms, workplaces, elementary schools, middle and high schools, trans ...
s for clothing and other belongings. The lockers can require a coin to be inserted in a slot, either as deposit or payment. There are usually showers – sometimes mandatory – before and/or after swimming. There are often also lifeguards to ensure the safety of users. Wading or paddling pools are shallow bodies of water intended for use by small children, usually in parks. Concrete wading pools come in many shapes, traditionally rectangle, square or circle. Some are filled and drained daily due to lack of a filter system. Staff chlorinate the water to ensure health and safety standards.


Competition pools

: ''See: #Dimensions (above) and Swimming (sport)#Competition pools'' The Fédération Internationale de la Natation (FINA, International Swimming Federation) sets standards for competition pools: long and at least deep. Competition pools are generally indoors and heated to enable their use all year round, and to more easily comply with the regulations regarding temperature, lighting, and automatic officiating equipment. An
Olympic-size swimming pool An Olympic-size swimming pool conforms to regulated dimensions that are large enough for international competition. This type of swimming pool is used in the Olympic Games, where the race course is in length, typically referred to as "long cour ...
(first used at the 1924 Olympics) is a pool that meets FINA's additional standards for the Olympic Games and for world championship events. It must be wide, divided into eight lanes of each, plus two areas of at each side of the pool. Depth must be at least . The water must be kept at and the lighting level at greater than 1500
lux The lux (symbol: lx) is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by the ...
. There are also regulations for color of lane rope, positioning of
backstroke flag Backstroke or back crawl is one of the four swimming styles used in competitive events regulated by FINA, and the only one of these styles swum on the back. This swimming style has the advantage of easy breathing, but the disadvantage of swimme ...
s (5 metres from each wall), and so on. Pools claimed to be "Olympic pools" do not always meet these regulations, as FINA cannot police use of the term.
Touchpads A touchpad or trackpad is a pointing device featuring a tactile sensor, a specialized surface that can translate the motion and position of a user's fingers to a relative position on the operating system that is made output to the screen. Touchp ...
are mounted on both walls for long course meets and each end for short course. A pool may be referred to as fast or slow, depending on its physical layout. Some design considerations allow the reduction of swimming
resistance Resistance may refer to: Arts, entertainment, and media Comics * Either of two similarly named but otherwise unrelated comic book series, both published by Wildstorm: ** ''Resistance'' (comics), based on the video game of the same title ** ''T ...
making the pool faster: namely, proper pool depth, elimination of currents, increased lane width, energy absorbing racing lane lines and gutters, and the use of other innovative hydraulic, acoustic and illumination designs.


Exercise pools

In the last two decades, a new style of pool has gained popularity. These consist of a small vessel (usually about 2.5 × 5 m) in which the swimmer swims in place, either against the push of an artificially generated water current or against the pull of restraining devices. These pools have several names, such as ''swim spas'', ''
swimming machine A swimming machine, or resistance swimming apparatus ,is a self-contained, pump-driven machine, that enables an athlete or recreational user to swim in place. A swimming machine is possible by accelerating the water past the swimmer or by suppor ...
s'', or ''swim systems''. They are all examples of different modes of
resistance swimming Resistance swimming is a form of swimming exercise undertaken either for athletic or therapeutic purposes. In optimal circumstances, it lends itself to any stroke the swimmer wishes to perform. Resistance swimming can be carried out either against ...
.


Hot tubs and spa pools

Hot tubs and spa pools are common heated pools used for relaxation and sometimes for therapy. Commercial spas are common in the swimming pool area or sauna area of a
health club A health club (also known as a fitness club, fitness center, health spa, and commonly referred to as a gym) is a place that houses exercise equipment for the purpose of physical exercise. In recent years, the number of fitness and health se ...
or fitness center, in men's clubs, women's clubs, motels and exclusive five-star hotel suites. Spa clubs may have very large pools, some segmented into increasing temperatures. In Japan, men's clubs with many spas of different size and temperature are common. Commercial spas are generally made of concrete, with a
mosaic A mosaic is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and were particularly pop ...
tiled interior. More recently with the innovation of the pre-form composite method where mosaic tiles are bonded to the shell this enables commercial spas to be completely factory manufactured to specification and delivered in one piece. Hot tubs are typically made somewhat like a
wine barrel Oak is used in winemaking to vary the color, flavor, tannin profile and texture of wine. It can be introduced in the form of a barrel during the fermentation or aging periods, or as free-floating chips or staves added to wine fermented in a vess ...
with straight sides, from wood such as
Californian redwood ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995:606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coastal ...
held in place by metal hoops. Immersion of the head is not recommended in spas or hot tubs due to a potential risk of underwater entrapment from the pump suction forces. However, commercial installations in many countries must comply with various safety standards which reduce this risk considerably. Home spas are a worldwide retail item in western countries since the 1980s, and are sold in dedicated spa stores, pool shops, department stores, the Internet, and catalog sales books. They are almost always made from heat-extruded Polymethyl methacrylate, acrylic sheet Perspex, often colored in marble look-alike patterns. They rarely exceed and are typically deep, restricted by the availability of the raw sheet sizes (typically manufactured in Japan). There is often a mid-depth seating or lounging system, and contoured lounger style reclining seats are common. Upmarket spas include various jet nozzles (massage, pulsating, etc.), a drinks tray, lights, LCD flat-screen TV sets and other features that make the pool a recreation center. Due to their family-oriented nature, home spas are normally operated from . Many pools are incorporated in a Coast Redwood, redwood or simulated wood surround, and are termed "portable" as they may be placed on a patio rather than sunken into a permanent location. Some portable spas are shallow and narrow enough to fit sideways through a standard door and be used inside a room. Low power electric immersion heaters are common with home spas. Whirlpool tubs first became popular in the U.S. during the 1960s and 1970s. A spa is also called a "jacuzzi" there, as the word became a generic after-plumbing component manufacturer; Jacuzzi introduced the "spa whirlpool" in 1968. Air bubbles may be introduced into the nozzles via an air-bleed venturi pump that combines cooler air with the incoming heated water to cool the pool if the temperature rises uncomfortably high. Some spas have a constant stream of bubbles fed via the seating area of the pool, or a footwell area. This is more common as a temperature control device where the heated water comes from a natural (uncontrolled heat) geothermal source, rather than artificially heated. Water temperature is usually very warm to hot – – so bathers usually stay in for only 20 to 30 minutes. Bromine or mineral sanitizers are often recommended as sanitizers for spas because chlorine dissipates at a high temperature, thereby heightening its strong chemical smell. Ozone is an effective bactericide and is commonly included in the circulation system with cartridge filtration, but not with sand media filtration due to clogging problems with turbid body fats.


Ocean pools

In the early 20th century, especially in Australia, Ocean pools in Australia, ocean pools were built, typically on headlands by enclosing part of the rock shelf, with water circulated through the pools by flooding from tidal tanks or by regular flooding over the side of the pools at high tide. This continued a pre-European tradition of bathing in rockpools with many of the current sites being expanded from sites used by Aboriginal Australians or early European settlers. Bathing in these pools provided security against both rough surf and sea life. There were often separate pools for women and men, or the pool was open to the sexes at different times with a break for bathers to climb in without fear of observation by the other sex. These were the forerunners of modern "Olympic" pools. A variation was the later development of sea- or harbour-side pools that circulated sea water using pumps. A pool of this type was the training ground for Australian Olympian Dawn Fraser. There are currently about 100 ocean baths in New South Wales, which can range from small pools roughly 25 metres long and "Olympic Sized" (50m) to the very large, such as the 50 × 100 m baths in Newcastle, New South Wales, Newcastle. While most are free, a number charge fees, such as the Bondi Icebergs Club pool at Bondi Beach. Despite the development of chlorinated and heated pools, ocean baths remain a popular form of recreation in New South Wales. A semi-natural ocean pool exists on the central coast of New South Wales; it is called The Bogey Hole.


Infinity pools

An infinity pool (also named ''negative edge'' or ''vanishing edge pool'') is a swimming pool which produces a visual effect of water extending to the horizon, vanishing, or extending to "infinity". Often, the water appears to fall into an ocean, lake, bay, or other similar body of water. The illusion is most effective whenever there is a significant change in elevation, though having a natural body of water on the horizon is not a limiting factor.


Natural pools and ponds

Natural pools were developed in central and western Europe in the early and mid-1980s by designers and landscape architects with environmental concerns. They have recently been growing in popularity as an alternative to traditional swimming pools. Natural pools are constructed bodies of water in which no chemicals or devices that disinfect or sterilize water are used, and all the cleaning of the pool is achieved purely with the motion of the water through biological filters and plants rooted hydroponically in the system. In essence, natural pools seek to recreate swimming holes and swimmable lakes, the environment where people feel safe swimming in a non-polluted, healthy, and ecologically balanced body of water. Water in natural pools has many desirable characteristics. For example, red eyes, dried-out skin and hair, and bleached swimsuits associated with overly chlorinated water are naturally absent in natural pools. Natural pools, by requiring a water garden to be a part of the system, offer different aesthetic options and can support amphibious wildlife such as snails, frogs, and salamanders, and even small fish if desired.


Zero-entry swimming pools

A ''zero-entry swimming pool'', also called a ''beach entry swimming pool'', has an edge or entry that gradually slopes from the deck into the water, becoming deeper with each step, in the manner of a natural beach. As there are no stairs or ladders to navigate, this type of entry assists older people, young children and people with Disability, accessibility problems (e.g., people with a physical disability) where gradual entry is useful.


Indoor pools

Indoor pools are located inside a building with a roof and are insulated by at least three walls. Built for year-round swimming or training, they are found in all climate types. Since the buildings around indoor pools are insulated, heat escapes much less, making it less expensive to heat indoor pools than outdoor pools (all of whose heat escapes). Architecturally, an indoor pool may look like the rest of the building, but extra heating and ventilation and other engineering solutions are required to ensure comfortable humidity levels. In addition to drainage and automatic pool covers, there are a number of ways to remove humidity in the air that is present in any wet indoor environment. Efficient Dehumidifier, dehumidification in the indoor pool environment prevents structural damage, lowers energy costs for cooling or heating, and improves the indoor climate to provide a comfortable swimming environment. Some colleges, universities, and high schools have buildings that use the term "natatorium" in their names, especially when the building houses more than just a swimming pool, for example a
diving Diving most often refers to: * Diving (sport), the sport of jumping into deep water * Underwater diving, human activity underwater for recreational or occupational purposes Diving or Dive may also refer to: Sports * Dive (American football), a ...
well or facilities for
water polo Water polo is a competitive team sport played in water between two teams of seven players each. The game consists of four quarters in which the teams attempt to score goals by throwing the ball into the opposing team's goal. The team with the ...
. The word ''natatorium'' was borrowed from Late Latin "place for swimming" into English in New England in 1890.


Other uses

Swimming pools are also used for events such as synchronised swimming, synchronized swimming,
water polo Water polo is a competitive team sport played in water between two teams of seven players each. The game consists of four quarters in which the teams attempt to score goals by throwing the ball into the opposing team's goal. The team with the ...
, canoe polo and underwater sports such as underwater hockey, underwater rugby, finswimming and sport diving (sport), sport diving as well as for teaching
diving Diving most often refers to: * Diving (sport), the sport of jumping into deep water * Underwater diving, human activity underwater for recreational or occupational purposes Diving or Dive may also refer to: Sports * Dive (American football), a ...
, Lifeguards, lifesaving and scuba diving techniques. They have also been used for specialist tasks such as teaching water-ditching survival techniques for aircraft and submarine crews and
astronaut An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
training. Round-cornered, irregular swimming pools, such as the Nude Bowl, were drained of water and used for vertical skateboarding.


Sanitation

Levels of bacteria and viruses in swimming pool water must be kept low to prevent the spread of diseases and pathogens. Bacteria, algae and insect larvae can enter the pool if water is not properly sanitized. Pumps, mechanical sand filters, and disinfectants are often used to sanitise the water. Chemical disinfectants, such as chlorine (usually as a hypochlorite salt, such as calcium hypochlorite) and bromine, are commonly used to kill pathogens. If not properly maintained, chemical sanitation can produce high levels of disinfection byproducts. Sanitized swimming pool water can theoretically appear green if a certain amount of iron salts or copper chloride are present in the water. Acesulfame potassium has been used to estimate how much urine is discharged by swimmers into a pool. * In a Canadian study it was estimated that swimmers had released 75 litres of urine into a large pool that had about 830,000 litres of water and was a third of the size of an olympic pool. Hot tubs were found to have higher readings of the marker. While urine itself is sterile, its degradation products may lead to asthma.


Covers

Swimming pool heating costs can be significantly reduced by using a pool cover. Use of a pool cover also can help reduce the amount of chemicals (chlorine, etc.) required by the pool. Outdoor pools gain heat from the sun, absorbing 75–85% of the solar energy striking the pool surface. Though a cover decreases the total amount of solar heat absorbed by the pool, the cover eliminates heat loss due to evaporation and reduces heat loss at night through its insulating properties. Most swimming pool heat loss is through evaporation. The heating effectiveness of a cover depends on type. A transparent bubble cover is the most effective, as it allows the largest amount of solar flux into the pool itself. Thermal bubble covers are lightweight Ultraviolet, UV-stabilized floating covers designed to minimize heat loss on heated swimming pools. Typically they are only fitted in spring and fall (autumn) when the temperature difference between pool water and air temperature is greatest. When used consistently they can raise average pool temperatures of an outdoor pool by around 18 °Fahrenheit (11 °Celsius) when combined with a well sized solar pool heating system, or about 11° Fahrenheit (6 °Celsius) without a solar heater but with full sun exposure. Bubble covers are typically applied and removed by being rolled up on a device fitted to one side of the pool (see illustration). Covers fall apart after four or five years due to sun exposure, overheating in the sun while off the pool, and chlorine attacking the plastic. Bubble covers should be removed during superchlorination. A vinyl cover absorbs more sunlight directly, allowing temperature to rise faster, but ultimately prevents the pool from reaching as high a temperature as a clear cover. Vinyl covers consist of a heavier material and have a longer life expectancy than bubble covers. Insulated vinyl covers are also available with a thin layer of flexible insulation sandwiched between two layers of vinyl. These covers are mandatory to be fitted to all pools in areas of Australia that have experienced drought since 2006. This is an effort to conserve water, as much water evaporates and transpires. An alternative to a continuous sheet of pool covering is multiple floating disks which are deployed and removed disk by disk. They cover most of the surface of the pool and offer evaporation reduction similar to continuous covers. Various types are available, for example opaque (for UV resistance and possible reduced algal growth), transparent (for esthetics), heavy and solid (for wind resistance), light and inflatable (for ease of handling). ; Liquid covers Liquid covers are also an option. They use a microscopically thin layer of liquid (such as cetyl alcohol) that sits on the water surface and reduces evaporation, which is one of the major sources of heat loss as well as water loss. Unlike other covers, the pool can be used while the liquid cover is in place, and the nontoxic material is safe for people as well as pumping/filtering systems. The liquid must be replenished regularly (monthly or more), and may not be effective in windy areas (since the wind will disperse the thin layer). ; Safety covers These covers are typically attached all winter, by hooked bungee cords or hooked springs connected to the pool deck, and are usually made in a variety of materials including coated or laminated vinyl or polypropylene mesh. They are custom designed to stop leaf debris from entering the pool but more importantly they also provide safety for animals and small children when designed and installed properly. The custom safety cover was invented in 1957 by Fred Meyer Jr. of Meyco Pool Covers when he found a dead animal in his pool. Today covers are made to meet ASTM International, ASTM safety barrier standards and have kept animals, people and even large vehicles out of the pool. They are not popular in warmer climates, due to the five to ten minutes it takes to fit/remove them, making them inconvenient for repeated application and removal.


Pool cover automation

A pool cover can be either manually, semi-automatically, or automatically operated. Manual covers can be folded and stored in an off site location. Pool cover reels can also be used to help manually roll up the pool cover. The reel, usually on wheels, can be rolled in or out of place. Semi-automatic covers use a motor-driven reel system. They use electrical power to roll and unroll the cover, but usually require someone to pull on the cover when unrolling, or guide the cover onto the reel when rolling up the cover. Semi-automatic covers can be built into the pool deck surrounding the pool, or can use reels on carts. Automatic covers have permanently mounted reels that automatically cover and uncover the pool at the push of a button. They are the most expensive option, but are also the most convenient. These reels can be run from either an external motor requiring a pit to be dug beside the pool or using an internal motor that spins the reel. Some pool covers fit into tracks along the sides of the pool. This prevents anything or anybody from getting into the pool. They even support the weight of several people. They can be run manually, semi-automatically, or automatically. Safety covers may be required by inspectors for public pools.


Winterization

In areas which reach freezing temperature, it is important to close a pool properly. This varies greatly between in-ground and above-ground pools. By taking steps to properly secure the pool, it lessens the likelihood that the superstructure will be damaged or compromised by freezing water.


Closing vinyl and fibreglass pools

In preparation for freezing temperatures, an in-ground swimming pool's pipes must be emptied. An above-ground pool should also be closed, so that ice does not drag down the pool wall, collapsing its structure. The plumbing is sealed with air, typically with rubber plugs, to prevent cracking from freezing water. The pool is typically covered to prevent leaves and other debris from falling in. The cover is attached to the pool typically using a stretch cord, similar to a bungee cord, and hooks fitted into the pool surround. The skimmer is closed off or a floating device is placed into it to prevent it from completely freezing and cracking. Floating objects such as life rings or basketballs can be placed in the pool to avoid its freezing under the cover. Sand or DE filters must be backwashed, with the main drain plug removed and all water drained out. Drain plugs on the Filter (water), pool filter are removed after the filter has been cleaned. The pool pump motor is taken under cover. Winter chemicals are added to keep the pool clean. The innovation of a composite construction of fiberglass, with an epoxy coating and porcelain ceramic tiles has led to the pre-form, composite-type with significant advantages over older methods; however, it also has increased sensitivity to metal staining. In climates where there is no risk of freezing, closing down the pool for winter is not so important. Typically, the thermal cover is removed and stored. Winter sunlight can create an algae mess when a cover that has been left on all winter is removed. The pool is correctly pH-balanced and super-chlorinated. One part algaecide for every 50,000 parts of pool water should be added, and topped up each month. The pool should be filtered for one to two hours daily to keep the automated chlorination system active.


Safety

Pools pose a risk of drowning, which may be significant for swimmers who are inexperienced, suffer from seizures, or are susceptible to a heart or respiratory condition. Lifeguards are employed at most pools to execute water rescues and administer first aid as needed in order to reduce this risk. Diving in shallow areas of a pool may also lead to significant head and neck injuries; diving, especially head-first diving, should be done in the deepest point of the pool, minimally , but desirably , deeper if the distance between the water and the board is great. Pools also present a risk of death due to drowning, particularly in young children. In regions where residential pools are common, drowning is a major cause of childhood death. As a precaution, many jurisdictions require that residential pools be enclosed with Pool fence, fencing to restrict unauthorized access. Many products exist, such as removable baby fences. The evidence for floating alarms and window/door alarms to reduce the risk of drowning is poor. Some pools are equipped with computer-aided pool safety camera, drowning prevention or other forms of electronic safety and security systems. Suspended ceilings in indoor swimming pools are safety-relevant components. The selection of materials under tension should be done with care. Especially the selection of unsuitable stainless steels can cause problems with stress corrosion cracking.


Dress code

In public swimming pools, dress code may be stricter than on public beaches, and in indoor pools stricter than outdoor pools. For example, in countries where women can be topless on the beach, this is often not allowed in a swimming pool, and a swimsuit must be worn. For men, wearing ordinary shorts and a T-shirt to go in the water at a beach may be considered acceptable, but pools usually require real swimsuits or other dedicated water wear. Swimming with regular clothes can potentially weigh a swimmer down should they need to be rescued. In France and some other European countries, board shorts are usually not allowed for "hygienic" reasons. In Nordic countries, in particular Iceland, rules about clothing and hygiene are especially strict. When diving from a high board, swimsuits are sometimes worn doubled up (one brief inside another) in case the outer suit tears on impact with the water.


See also

* Automated pool cleaner * Bather load * Lido (swimming pool), Lido * List of water games * Neutral buoyancy pool * Pool fence * Pool noodle * Respiratory risks of indoor swimming pools * Swimming pool service technician * Uniform Swimming Pool, Spa and Hot Tub Code * Urine-indicator dye


References


External links

* {{Authority control Swimming pools, Bodies of water Garden features Sports venues by type