Jellyfish Lake, or "Ongeim’l Tketau" as it is called in Palauan, is one of approximately 70 marine lakes scattered throughout the limestone “rock islands” of the southern portion of the main Palau archipelago. Ongeim’l Tketau is one of at least eight lakes in Palau that contain large populations of the golden jellyfish, the moon jellyfish, or both. However, with the exception of Ongeim’l Tketau, all others are closed to tourism under the Koror State Rock Islands Conservation Act.
Palau’s remarkable rock islands formed millions of years ago as forces slowly pushed coral reefs out of the ocean. The marine lakes are the product of the porous nature of the islands in relation to height of the surrounding ocean, which, over the last 25,000 years, has changed in response to changes in the earth’s climate.
During the earth’s most recent glacial period, approximately 20,000 years ago, vast amounts of water formed massive glaciers, and sea level was 330 feet lower than today. As climate warmed, the glaciers gradually melted returning water to the seas. Approximately 10 to 12,000 years ago, sea level reached a sufficient height to flood the channels and fissures of the rock islands, creating marine lakes in depressions within the islands. (Imagine placing a colander in an empty sink and then filling the sink with water.) The marine lakes remain connected to the sea and can be witnessed as the tides rise and fall within the lakes in response to tidal changes in the surrounding lagoon.
Jellyfish Lake is unique among the rare, only one life form dominates. Here the golden jellyfish (Mastigias sp.), for which the lake is famous, has drifted in during its larval stage and flourished.
Your tour guide can assist you in obtaining a “Rock Island Visitors Permit” issued by the Koror State Government and then you can visit Jellyfish Lake.
Lake Ongeim’l Tketau is on one of the hundreds of Rock Islands that are spread out over more than 23 miles between the islands of Koror and Peleliu. It is only accessible by boat, and then visitors will have to traverse a ridge, which separates the lake from the surrounding lagoon. The trail is short (less than 1/4 of a mile) with relatively steep and rocky terrain.
Visitors emerge from the jungle onto a floating dock situated in the northwest corner of the lake. The jellyfish can be seen by swimming out of the channel in front of the dock and heading toward the center of the lake.
You must complete two tasks in order to log this cache:
1. Post a picture of yourself and your GPSr on either the arrival dock on the ocean side, or the floating dock on the lake.
2. Take a GPS elevation reading at sea level on the ocean side, an elevation reading on top of the ridge, and an elevation reading at the lake level; use you readings and determine if the sea water has seeped in and has actually filled the lake to the same level of the sea. If you are unable to use your GPS for elevation readings; estimate the size of the area that the lake covers. E-mail us the action you took and your findings.
Don't wait to log your find, post your picture and send the e-mail. If there is a problem with your findings we will contact you.
You must complete the requirements to adhere to the EarthCache guidelines or your log will be deleted.