Jellyfish Lake, Eil Malk Island, Palau, Pacific Ocean

Scuba diving by tourists in the lake is not allowed. Two reasons are put forward for this:
- The bubbles from scuba tanks can harm the jellyfish if they collect beneath their bell.
- The anoxic layer that begins at about 15 meters contains high concentrations of hydrogen sulfide which can be absorbed through the skin of a diver which can lead to death.
Jellyfish Lake is currently the only one of Palau's marine lakes open to tourists.