Kakaban island is part of the

Derawan Islands The Derawan Islands ( id, Kepulauan Derawan) are in the province of East Kalimantan in Indonesia. They consist of 31 islands, most well known among these are the islands of Derawan, Kakaban, Maratua, and Sangalaki. There are also numerous submerg ...

East Kalimantan East Kalimantan ( Indonesian: ) is a province of Indonesia. Its territory comprises the eastern portion of Borneo. It had a population of about 3.03 million at the 2010 census (within the current boundary), 3.42 million at the 2015 census, and 3 ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

. The island has an area of and is quite steep. Its limestone cliffs are covered with dense

jungle A jungle is land covered with dense forest and tangled vegetation, usually in tropical climates. Application of the term has varied greatly during the past recent century. Etymology The word ''jungle'' originates from the Sanskrit word ''ja� ...

right down to the water's edge. The wall drops to , and currents can be strong with upwelling, downcurrent and reversing directions. The most distinctive feature is the huge brackish water lake in the middle of the island, in the local dialect Kakaban means "hug" as the island hugs the lake from the surrounding seawater.

Jellyfish Lake

In the middle of this island is a

mangrove A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...

-fringed lake, slightly above sea level, where thousands of jellyfish live, making it interesting for diving. The jellyfish consist of four different species which do not have the ability to harm humans with their stinging cells. They are

Aurelia aurita ''Aurelia aurita'' (also called the common jellyfish, moon jellyfish, moon jelly or saucer jelly) is a species of the genus '' Aurelia''. All species in the genus are very similar, and it is difficult to identify ''Aurelia'' medusae without genet ...

with a transparent body, Tripedalia cystophora which is fingertip size,

Mastigias papua The spotted jelly (''Mastigias papua''), lagoon jelly, golden medusa, or Papuan jellyfish, is a species of jellyfish from the Indo-Pacific oceans. Like corals, sea anemones, and other sea jellies, it belongs to the phylum Cnidaria. ''Mastigias p ...

is like a green-brown bulb, and

Cassiopea ornata ''Cassiopea ornata'' are one of many Cnidarian species called the upside-down jellyfish. This pelagic jellyfish primarily lives in tropical waters, off the coast of Australia in shallow lagoons and around mangrove trees. The name "upside-down je ...

which is an upside-down jellyfish with upright

tentacles In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work mainl ...

. Although they cannot sting humans, they still have poison and can sting their prey. Similar lakes exist in the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

(

Siargao Siargao is a tear-drop shaped island in the Philippine Sea situated 196 kilometers southeast of Tacloban. It has a land area of approximately . The east coast is relatively straight with one deep inlet, Port Pilar. The coastline is marked by a s ...

) Palau, with Jellyfish Lake being the best known. The lake has warm brackish water and the bottom is covered with marine green algae. There are other animals, including sea cucumbers,

gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising more than 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the ...

, sea anemones,

tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ...

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

nudibranch Nudibranchs () are a group of soft-bodied marine gastropod molluscs which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to match, ...

s, orange purple clams and yellow clams on the branches, and

snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more j ...

s. The lake is at most deep with poor visibility and is 10 minutes walk from the beach. Kakaban was probably uplifted during the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

era and seawater was trapped, forming a landlocked marine lake. The water is now a mixture of saltwater and fresh water from rain.

Barracuda Point

This is a steep wall, where the current brings large

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

s like whitetip sharks,

leopard shark The leopard shark (''Triakis semifasciata'') is a species of houndshark, in the family Triakidae. It is found along the Pacific coast of North America, from the U.S. state of Oregon to Mazatlán in Mexico. Typically measuring 1.2–1.5 m (3.9� ...

jack Jack may refer to: Places * Jack, Alabama, US, an unincorporated community * Jack, Missouri, US, an unincorporated community * Jack County, Texas, a county in Texas, USA People and fictional characters * Jack (given name), a male given name, ...

tuna A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae ( mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max len ...

, snapper and

barracuda A barracuda, or cuda for short, is a large, predatory, ray-finned fish known for its fearsome appearance and ferocious behaviour. The barracuda is a saltwater fish of the genus ''Sphyraena'', the only genus in the family Sphyraenidae, which was ...

. Drift diving can be done with the help of a grab line permanently secured across a relatively flat area on the upcurrent side of the point. Currents can be fierce with down currents.

Blue Light Cave

The

cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...

starts at a crack at deep and descends through a narrow chimney. At about the chimney opens into a large cavern that extends for about . The exit is a long vertical crack in the wall at . The name of the cave comes from the blue light of the sea which is seen from the cavern.

References

Derawan Islands Landforms of East Kalimantan Islands of Kalimantan {{EKalimantan-geo-stub