“Fluorescent green, the lake is home to millions of jellyfish that do not sting. They were pulsating orange blobs, and ranged in size from Ping-Pong balls to bowling balls.”
- Ian Urbina, from his book The Outlaw Ocean on Palau’s famous Jellyfish Lake.
After a two year closure, Palau’s famous Ongeim'l Tketau or Jellyfish Lake on Mecherchar Island has reopened. The saltwater lake is known worldwide for its profusion of bright orange, harmless, and beautiful jellyfish, which represent a unique subspecies of Mastigias papua etpisoni jellies. Jellyfish Lake is a UNESCO World Heritage Site, and one of the best places in the world to enjoy the otherworldly experience of swimming amongst a sea of frilly jellies.
In 2005, the lake’s population of jellyfish peaked at an estimated 30 million individuals, but the population numbers plummeted in 2016 due to an El Niño weather event that brought drought conditions and warming waters. High levels of sunscreen in the water may also have contributed, although there is not enough evidence to know for certain. With support from a self-imposed ban by tour operators, Palauan President Tommy Remengesau called for the lake’s closure in order to allow for the lake and jellyfish populations to recover.
There are seventy marine lakes within the Palau archipelago, and only five that contain jellyfish. Of these five, Jellyfish Lake is the only one open to visitors. With no natural predators, the jellyfish spend the day slowly making their way from one end of the lake to the other, following the path of the sun. The sunlight supports algae growth, food for the colorful jellies. While they haven’t completely lost their stinging ability, their stings are too light for humans to feel.
Oceanic Society board member, Dr. Sylvia Earle, founder of Mission Blue, snorkels in Jellyfish Lake during a joint Hope Spot Expedition with Oceanic Society and Mission Blue in Palau.
© Kip Evans Mission Blue
Palau has taken strides to ensure the protection and longevity of the jellyfish and the unique experience of swimming with them. For example, diving is prohibited in Jellyfish Lake in order to prevent mixing the two stratified layers within the lake. The top layer is less saline, which makes it ideal for the jellies and other wildlife like fish and plankton. The lower layer, on the other hand, contains dangerous levels of hydrogen sulfide, which can be toxic to both humans and wildlife. Beyond the ban on diving, visitors to Jellyfish Lake must wear environmentally friendly sunscreen that has been applied at least 30 minutes before entering the water. Visitors are also encouraged to sign the Palau pledge, a promise to protect and preserve Palau’s natural beauty, cultural heritage, and environment.A once in a lifetime adventure, Jellyfish Lake should be on any snorkel enthusiasts bucket list. The unique experience is one of many on our Palau: Snorkeling the Rock Islands expedition, with trip dates available multiple times throughout the year. Don’t miss your chance to swim with these remarkable and endearing jellies!
Huntley Penniman is an Oceanic Society social media specialist and communications strategist. From diving to conservation and environmental communications, her passion lies in learning more about the wildlife that lives under the surface of the ocean. Huntley holds a B.S. in Biology from Boston College and a Master’s in Marine Biodiversity and Conservation from Scripps Institution of Oceanography.