There’s a lake in the Pacific island chain of Palau where millions of boneless creatures bob in the water. Most are a small species called golden jellyfish.
Jellyfish Lake, also known as Ongeim’l Tketau (ohn-yay-yeem-ul kah-tow), is one of dozens of marine lakes in Palau. These bodies of water are fed by the sea and rain. They formed about 15,000 years ago, after the last ice age ended. During that period, glaciers, or enormous ice sheets, covered much of Earth’s large landmasses. As the ice melted, sea levels rose. Water flowed through tiny holes in the rock of Palau’s islands. It filled low spots, forming lakes. The seawater swept in young jellyfish.
Jellyfish Lake is Palau’s only marine lake open to visitors. Although the golden jellyfish can give a mild sting, the lake is still a popular swimming spot. Tourists aren’t allowed to touch or remove jellies. In 2016, the adult jellyfish population crashed to zero. Scientists think the lake became too warm after an extreme drought, a long period with little or no rain. Some young jellyfish remained, and by 2019, jellyfish numbers had recovered.