Jellyfish Lake (Danau Ubur-Ubur)

A landlocked marine lake on Pulau Togean connected to the sea through limestone fissures, Jellyfish Lake hosts millions of golden jellyfish (Mastigias papua) that have lost their sting through evolutionary isolation. Snorkellers and divers drift through clouds of pulsating jellyfish in water that transitions from clear turquoise near the surface to a purple-black anoxic layer below 12 m. Freediving is strongly preferred as bubbles harm the jellies — those who use scuba must stay in the upper 10 m. The lake also shelters endemic goby species and mangrove archer fish visible along the shoreline.