A journey through Jellyfish Lake on Eli Malk Island in the Republic of Palau by Sarosh Jacob.
Music: Nude by Radiohead.
Twelve thousand years ago, these jellyfish became trapped in a natural basin on the island when the ocean receded. With no predators among them for thousands of years, they evolved into a new species that lost most of their stinging ability as they no longer had to protect themselves. They are pretty much harmless to humans although some people with very sensitive skin may get a minor irritation from them.
It is not possible to scuba dive in this lake because the nutrient rich layer at around 50 feet and below contains hydrogen sulphide which is highly toxic to humans. If a scuba diver was to swim in that layer, the toxins would enter the body through the skin and that exposure could be fatal. Snorkeling however, is perfectly safe.