Jellyfish Lake is a true wonder of nature, and part of Palau's only World Heritage Site. As the name suggests, it's a lake filled with jellyfish. To add to the wonder, the lake is placed on a jungle covered tropical island in the most stunning azure blue sea. Since the jellyfish are harmless (only stings very very little), it's possible to swim with them in the lake. The Palau government want to protect the fragile Jellyfish Lake, so you need to join a tour (and get a permit) and there are restrictions, like no touching. However, the concentration of jellyfish can in some of areas of the lake be so dense, that the jellyfish gently bump into you. It's an expensive excursion (even more as it's usually combined with snorkeling or diving among Rock Islands), but totally worth it.