One of the coolest experiences I’ve ever had was to be able to swim alongside thousands of jellyfish, not worried about being stung! Yes, you can actually swim with jellyfish…safely…in Palau!
Welcome to Ongeim’l Tketau, or Jellyfish Lake as it is more well-known. Ongeim’l Tketau can be found in a rocky, uninhabited part of the gorgeous atolls of Palau…a diver’s and a dreamer’s paradise.
The lake is full of golden and moon jellyfish that migrate across the lake in a distinct pattern in search of food and sun. They puff along, like little busy plastic balls…soft to touch and fascinating to watch.
The lake is rather turgid, as you can see from the cloudy photograph my snorkeling buddy took. In fact, the lake is stratified into two distinct parts — the top 15 meters is oxygen-rich, where all of the jellyfish live, and from 15 meters down to the bottom of the lake (the average depth being about 30 meters) has no oxygen whatsoever and is rich in hydrogen sulfide, which if absorbed in large quantities can be deadly…and this is why scuba diving is not permitted in the lake. A lake with two distinct layers is termed a “meromictic” lake, which means that these layers never mix, and it is believed that the fissures and tunnels in the limestone that connect the lake to the ocean (through tidal water) are what keeps these layers separate. There are only a couple hundred meromictic lakes in the world.
These jellyfish actually have nematocytes, or stinging cells! But, their cells are not powerful enough like most other jellyfish to have any affects on humans. So, it is safe to swim amongst them. Some biologists believe that the jellyfish have evolved over time to lose their stinging capability. Spotted jellyfish with nasty stingers live in the surrounding lakes that don’t have the stratified layers. The golden jellyfish in this lake closely resemble the spotted jellyfish, except for a loss of defensive characteristics like stingers and clubs. Since Jellyfish Lake contains no predators, it may be that the golden jellyfish have evolved to lose their defense mechanisms.