Rock Islands

Where

Koror State, Republic of Palau
western Pacific

Coordinates

7.25° N
134.40° E

Islands

445 (UNESCO)
250–300 (Wikipedia, other sources)

Marine lakes

52 (UNESCO)

World Heritage

2012, as the
Rock Islands Southern Lagoon

Palau Pledge

Signed by every visitor
since 7 December 2017

Advisory

Palau Level 1
(Rock Islands: Level 2)

The short answer

The Rock Islands, Chelbacheb in Palauan, are a group of small limestone islands in Koror State, in the Republic of Palau in the western Pacific. UNESCO inscribed them in 2012 as the Rock Islands Southern Lagoon, a property of 100,200 hectares that it describes as 445 uninhabited limestone islands of volcanic origin; Wikipedia gives between 250 and 300 islands, according to different sources, with an aggregate land area of 42 km². Many are undercut at the waterline into mushroom shapes. UNESCO counts 52 marine lakes among them, more than at any other site in the world. The best known is Ongeim’l Tketau, Jellyfish Lake, on the island of Eil Malk. Visitors reach the islands by boat from Koror.

Why it's worth knowing

Palau asks every visitor for a promise, and it asks on behalf of its children. Since 7 December 2017, every arriving visitor has signed the Palau Pledge, which is stamped into their passport in place of an ordinary entry stamp and signed there. National Geographic reported Palau as the first country to require every incoming visitor to sign an environmental pledge stamped into their passport; a presidential directive, No. 17-29, instructs Palau’s immigration officials to use the Palau Pledge entry stamp. The pledge, which Global Voices and Palau’s Island Times describe as written with the help of Palau’s children, is addressed to them directly. It begins: “Children of Palau, I take this pledge, as your guest, to preserve and protect your beautiful and unique island home,” and it ends with a promise to leave “only footprints that will wash away.”

The islands it protects are made of old reef. UNESCO describes their limestone as of volcanic origin and the remains on them, of stone villages, burial sites and rock art, as evidence of small island communities over some three thousand years. Their shape is the work of the sea and of the animals living at its edge. Many of the islands, Wikipedia records, are mushroom-shaped, with a narrower base at the intertidal notch; the notch comes from erosion and from a dense community of sponges, bivalves, chitons, snails, urchins and other animals working at the rock.

The field notes

Fifty-two lakes

UNESCO describes the Southern Lagoon as having the highest concentration of marine lakes anywhere: bodies of seawater cut off from the ocean by land. Its 52 lakes are at different stages of geological and ecological development, it says, from lakes well connected to the sea to lakes so isolated that their species differ notably from the lagoon’s, including some found nowhere else. The surrounding reef supports more than 385 species of coral, by UNESCO’s count, along with dugong and at least thirteen species of shark.

The jellyfish lake

Ongeim’l Tketau, on Eil Malk, is around 12,000 years old, Wikipedia says: it filled when sea levels rose after the last ice age, and it still exchanges water with the lagoon through fissures and tunnels in the limestone. It is about 460 metres long and averages 30 metres deep. Two jellyfish live in it, the golden jellyfish Mastigias papua etpisoni and a moon jellyfish, and the golden jellyfish migrate across the lake each day. Their numbers swing hard. The Palau Visitors Authority records highs of around 30 million and collapses to nearly none in 1998–99 and 2016–17, both followed by recovery, and a fall to about 34,000 in mid-2022 as the water rose above 31.5 °C, the threshold it gives for successful reproduction. A Palau government release of December 2018 announced the lake open to visitors again after the 2016–17 collapse.

Deep water

Below about 15 metres the lake is anoxic, Wikipedia records, with high concentrations of hydrogen sulfide that are dangerous to divers. Visitors may snorkel in the lake; scuba diving by tourists is not allowed, both for that reason and to protect the jellyfish.

Getting there

How to get there. Palau’s international airport is on Babeldaob, about 6 km from Koror, with flights from Guam, Manila, Taipei, Tokyo and Brisbane among others, by Wikipedia’s list. Day tours, snorkel trips and dive boats to the Rock Islands leave from Koror.

When to go. Check the state of the jellyfish lake before planning a trip around it: its golden jellyfish have collapsed and recovered more than once, and the Palau Visitors Authority publishes updates.

What to arrange ahead. A boat tour or dive operator in Koror, and the Koror State permit. By the Palau Visitors Authority’s account, a Rock Islands permit costs US$50 and a Jellyfish Lake permit, which includes it, US$100, each valid for five days; tour companies and the Koror State ranger office issue them. The Pledge itself is signed on arrival.

Safety. The State Department has Palau at Level 1, exercise normal precautions (advisory dated 7 January 2026), but rates the Rock Islands and the smaller outlying islands Level 2, exercise increased caution: there is no emergency medical infrastructure there, and reaching lifesaving care can take a boat ride of several hours. It also advises increased caution on Peleliu because of unexploded Second World War ordnance. Go with an established operator, and in the jellyfish lake stay near the surface.

Common questions

What is the Palau Pledge?

The Palau Pledge is a promise that every visitor to Palau has signed since 7 December 2017, stamped into their passport on arrival and addressed to the children of Palau. It begins “Children of Palau, I take this pledge, as your guest, to preserve and protect your beautiful and unique island home”. National Geographic reported Palau as the first country to require such a pledge of every visitor.

Why are Palau's Rock Islands shaped like mushrooms?

Many of Palau’s Rock Islands are undercut at the waterline into a notch, which leaves a forested top standing on a narrower base. Wikipedia attributes the notch to erosion and to a dense community of sponges, bivalves, chitons, snails and urchins living and feeding at the limestone’s intertidal edge.

How many Rock Islands are there in Palau?

UNESCO describes the Rock Islands Southern Lagoon World Heritage site in Palau as 445 uninhabited limestone islands across 100,200 hectares. Wikipedia gives between 250 and 300 islands, according to different sources, with a combined land area of 42 km². The difference depends on what counts as an island.

Is Jellyfish Lake in Palau open?

Koror State reopened Jellyfish Lake (Ongeim’l Tketau), on Eil Malk in Palau’s Rock Islands, to visitors in December 2018 after a collapse of its golden jellyfish, according to a Palau government release. The numbers swing with water temperature: the Palau Visitors Authority records near-total collapses in 1998–99 and 2016–17 and a fall to about 34,000 in 2022. Check the current status with the authority or a Koror operator.

Can you scuba dive in Jellyfish Lake?

No. Scuba diving by tourists is not allowed in Jellyfish Lake in Palau, according to Wikipedia: the water below about 15 metres is anoxic, with dangerous concentrations of hydrogen sulfide, and divers can harm the jellyfish. Snorkelling is permitted.

Do you need a permit to visit the Rock Islands?

Yes. Koror State in Palau requires a permit for the Rock Islands. The Palau Visitors Authority gives a Rock Islands permit as US$50 and a Jellyfish Lake permit, which includes it, as US$100, each valid for five days, issued by tour companies or the Koror State ranger office.

When did the Rock Islands become a World Heritage Site?

UNESCO inscribed Palau’s Rock Islands Southern Lagoon on the World Heritage List in 2012, under both natural and cultural criteria. It covers 100,200 hectares, including 445 limestone islands and 52 marine lakes, and remains of stone villages, burial sites and rock art.

Is Palau safe to visit?

The U.S. State Department has Palau at Level 1, exercise normal precautions (advisory dated 7 January 2026), but rates the Rock Islands and smaller outlying islands Level 2, exercise increased caution, because they have no emergency medical infrastructure and lifesaving care can be several hours away by boat. It also advises increased caution on Peleliu for unexploded Second World War ordnance.

Notes on sources. This entry draws on UNESCO’s World Heritage listing for the Rock Islands Southern Lagoon (whc.unesco.org), reached through its indexed text, for the inscription in 2012 and its criteria, the 100,200 ha, the 445 uninhabited limestone islands of volcanic origin and their mushroom shapes, the 52 marine lakes and their stages of development and endemic species, the 385 coral species, dugong and thirteen shark species, and the stone villages, burial sites and rock art over some three millennia; on National Geographic (nationalgeographic.com) for Palau as the first country to require every visitor to sign a stamped environmental pledge, the pledge in place of the ordinary entry stamp, and its launch on 7 December 2017; on the Government of Palau (palaugov.pw) for Presidential Directive 17-29 on the Palau Pledge entry stamp and the December 2018 release reopening the jellyfish lake; on Global Voices (globalvoices.org) and the Island Times for the pledge’s writing with the help of Palau’s children and its wording; and on the Palau Visitors Authority (pristineparadisepalau.com) for the permit prices and validity, their issuers, and the history of the golden jellyfish population, including the 30 million highs, the collapses of 1998–99 and 2016–17, the 2022 fall to about 34,000 and the 31.5 °C threshold. Wikipedia’s articles on the Rock Islands, Jellyfish Lake and Roman Tmetuchl International Airport, and the references they cite, supplied the Palauan name Chelbacheb, the count of 250 to 300 islands and their 42 km², the intertidal notch and the animals that make it, the lake’s age, its connection to the lagoon, its dimensions, its two jellyfish and their migration, the anoxic layer and the ban on scuba, and the airport’s location and routes. The island counts are given with their parties, since they depend on definition. The jellyfish are not given a current number: the latest official figure found is from 2022, and an operator’s report of a few thousand in 2025 was not confirmed by an official source. The Pledge is described as it is signed, not as a legal penalty, because the penalty provisions were not checked. Travel advisory: the United States has Palau at Level 1, exercise normal precautions (7 January 2026), with the Rock Islands and smaller outlying islands at Level 2 for the lack of emergency medical care, and increased caution on Peleliu for unexploded ordnance. Checked 3 October 2026 against the State Department’s advisory page, read through its indexed text; the department’s RSS feed still carries an earlier version, dated 6 August 2024, with no area notes. Written and fact-checked by SockMonkey. Last reviewed 3 October 2026.