Jellyfish Lake, Kakaban Island

Berau · East Kalimantan · Indonesia

Kakaban Island's Jellyfish Lake is one of the most singular natural wonders in the diving world. This ancient brackish lake, nestled in the interior of uninhabited Kakaban Island in the Derawan Archipelago off East Kalimantan, Borneo, is one of only two places on Earth where visitors can swim freely among millions of stingless jellyfish. Over millions of years, four jellyfish species trapped in this landlocked body of water evolved to shed their stinging cells entirely, creating an otherworldly snorkeling experience found nowhere else in Indonesia. The lake itself is approximately 17 meters deep with warm brackish water, a green algae-covered bottom, and visibility that varies from 5 to 10 meters depending on conditions. Swimmers enter from a short jungle trail over raised coral limestone and find themselves surrounded almost immediately by pulsing clouds of translucent golden, moon, box, and spotted jellyfish. The sensation of floating among millions of harmless gelatinous creatures in dappled forest light is genuinely unique in the natural world. While scuba diving is not permitted inside the lake to protect its delicate ecosystem, Kakaban Island's outer reefs deliver some of the Derawan Archipelago's finest underwater terrain. The island's walls drop precipitously to 180 meters, with healthy hard coral coverage, gorgonian fans, and abundant reef fish at recreational depths. Combined with the broader Derawan diving circuit, which includes manta cleaning stations at Sangalaki, green turtle nesting beaches, whale shark encounters, and the muck diving of Derawan's jetty, the Kakaban experience sits within one of Indonesia's most diverse and rewarding dive regions. Water temperatures around the Derawan Archipelago range from 28 to 31 degrees Celsius year-round. The optimal visiting season is March through October, when seas are calmest and the jellyfish population in the lake is at its peak. Getting here requires commitment, with flights to Berau followed by a multi-hour boat transfer, but the reward is access to one of the planet's truly irreplaceable underwater experiences.