Danau Mariona, also known as Jellyfish Lake, is one of the saline lakes in Indonesia where it is possible to swim with stingless jellyfish. The others are located in Kalimantan and Raja Ampat, respectively.

This site is not categorized as a diving site because fins are not allowed, but the uniqueness of the evolution of the jellyfish here is worth a visit. The absence of natural predators has made these jellyfish lose their ability to sting. This lake has two species: the moon jellyfish and the white-spotted jellyfish.

But the stingless jellyfish are not the only ones inhabiting this saltwater lake. Sponges, tunicates, mussels, sea cucumbers, gobies, needlefish, and rabbitfish are relatively abundant here, creating a unique ecosystem in the Togian Islands.