Discovering Palau's Living Treasure

Ongeim'l Tketau ( 'Fifth Lake')

Nestled within the embrace of Eil Malk island, part of the enchanting Rock Islands group, lies a treasure trove like no other - Jellyfish Lake. Here, millions of golden jellyfish, a subspecies called Mastigias papua etpisoni, grace the waters, a spectacle found exclusively in this marine sanctuary. Known by the Palauans as the “Fifth Lake” out of 7 marine lakes containing these evolutionary marvels, Ongeim'l Tketau is just 45 minutes away from Koror.

The Dance of Ages 

This marvel of nature boasts an impressive history, with its roots dating back approximately 12,000 years. Its age, determined by depth, sediment thickness, and the rise of sea levels since the last ice age, tells a tale etched in time. 

Jellyfish Lake holds within its depths a unique stratification: an upper oxygen-rich layer, or mixolimnion, and a lower anoxic layer, or monimolimnion. This delicate balance, where oxygen tapers to zero at 15 meters, creates a world of wonder where life takes on a rhythm all its own. For divers, the anoxic layer's hydrogen sulphide proves hazardous, but for snorkelers who steer clear, it holds no danger.

Here, the lake's unique meromictic nature shines, one of only 200 such saline lakes worldwide. It's a haven for distinct species, delicately connected to the ocean yet isolated enough to foster its own unique inhabitants. In the embrace of Jellyfish Lake, a remarkable ecosystem unfolds. The golden jellyfish, reliant on symbiotic algae for sustenance, gracefully migrate across the lake each day, guided by the sun's embrace and avoiding the shadows where sea anemones, their natural predators, await.

The Dance of Recovery

In 1998, the golden jellyfish faced a formidable challenge, a decline attributed to an El Niño event. However, nature's resilience prevailed, and by 2012, they had rallied, a testament to their remarkable spirit. The El Niño drought in 2015/2016 brought another challenge, but by late 2018, the golden jellyfish began their steady return.

Beyond its natural splendor, this living marvel grapples with an unsettling challenge: The intrusion of invasive species, a consequence of human activity and tourism, now stands as a substantial concern. Through vigilant monitoring and dedicated research, the research institutes in Palau such as the Coral Reef Research Foundation (CRRF) tirelessly monitors and studies this unique ecosystem to preserve this delicate ecosystem. 

Preservation through Respect

While the golden jellyfish have remnant stinging cells, they pose little threat to humans. Access to this living treasure comes with responsibility: to protect the jellyfish and ensure safety, we uphold a strict snorkeling-only policy and we recommend guests to opt for sun-protective clothing rather than sunscreen. If sunscreen is necessary, please apply it sparingly, and choose an eco-friendly option. 

Access to the Jellyfish Lake requires a Rock Islands/Jellyfish Lake pass, valued at $100 for 10 days.  

Embark on a journey into the heart of this living marvel, where golden jellyfish and stratified waters invite you to witness the wonders of Palau's aquatic realm. Here, nature weaves a tapestry of life, and you're invited to be a part of its exquisite dance.