Jellyfish Lake, Eil Malk, Palau

Jellyfish Lake: What Palau’s Most Famous Swim Actually Involves

Jellyfish Lake is a marine lake on Eil Malk Island in Palau’s Rock Islands, a UNESCO World Heritage Site. The lake is connected to the ocean through fissures in the limestone rock but is isolated enough that its ecosystem has evolved independently over thousands of years. The golden jellyfish (Mastigias papua etpisoni) and the moon jellyfish (Aurelia aurita) that live in the lake are sting-reduced or essentially harmless to humans - their prey is algae rather than other marine animals, and their nematocysts are too small to penetrate human skin in any meaningful way. Millions of them migrate horizontally across the lake daily, following sunlight to maintain the symbiotic algae in their tissue.

The lake was closed to visitors from 2016 to 2019 after jellyfish populations crashed, possibly due to El Nino conditions affecting water temperature and stratification. It reopened with new regulations.

Getting in

Palau’s Rock Islands permit is required to visit Jellyfish Lake: USD 100 for the permit, which includes multiple Rock Islands sites. The permit is separate from the palau pledge and tourism fee collected on arrival. Most visitors access the lake through day-trip boat operators from Koror, the main island. The boat ride to Eil Malk takes 30-45 minutes. A standard day tour combining Jellyfish Lake with snorkelling at one or more Rock Islands reefs costs around USD 100-200 per person depending on the operator and what is included.

The lake itself sits 10 minutes’ walk inland from the boat dock on Eil Malk. The trail is steep in places. Scuba diving is prohibited in the lake (depth changes disturb the hydrogen sulfide layer below 15 metres, which kills jellyfish); snorkelling is permitted.

In the water

The lake’s surface is warm (28-30 degrees Celsius). The jellyfish density varies by time of day and season - highest during mid-morning migration. Swimming among them is an unusual sensation: the water is gelatinous in a way that is difficult to describe, and at peak density the jellyfish are everywhere at arm’s reach. They do not sting. Some people experience mild skin irritation from prolonged exposure to the lake water; reef-safe sunscreen is required rather than recommended.

Visibility in the lake is several metres horizontally. The jellyfish cluster near the surface and thin out below 5-6 metres. The surrounding mangroves and the limestone cliffs above the lake make the setting distinctive.

The Rock Islands more broadly

Palau’s Rock Islands (Chelbacheb) are 445 limestone islands in an area of about 36 square miles. The diving in the channels between them - Blue Corner, German Channel, Jellyfish Lake’s sister sites - is among the best in the world for large pelagic fish: grey reef sharks, manta rays, Napoleon wrasse in large numbers. Blue Corner involves a reef wall where current brings sharks and fish in substantial concentrations, and divers hook into the reef with reef hooks to hold position against the current.

Koror accommodation

Palau has no major international hotel brands. The Palau Pacific Resort is the most established higher-end option (USD 200-300 per night). The Fish n Fins dive resort and DW Motel are mid-range options used heavily by divers. Budget accommodation exists but choice is limited. Rooms book out well in advance during the October-November and March-April dive seasons.