Jellyfish Lake, Palau

Lake Locations:

Palau -

Also known as:  Ongeim'l Tketau , Fifth Lake

Small but spectacular, Jellyfish Lake on Eil Malk Island in the tiny nation of Palau draws thousands of visitors each year. There are no resorts at Jellyfish Lake; the sole attraction is swimming-specifically snorkeling-with millions of tiny jellyfish!. The small marine lake is connected to the nearby lagoon via fissures and cracks that allow sea water to enter the lake with the tide. This keeps the lake refreshed in the upper part of the waters and allows it to maintain its saline balance. The island itself is one of the Rock Islands. These mostly uninhabited islands can be reached by boat from the city of Koror about 15 miles away. The islands contain about 70 marine lakes; five of them hold the unusual yellow jellyfish. Jellyfish Lake is the only one which is accessible to the public.

The tiny 13 million jellyfish in Jellyfish Lake have evolved to become basically ‘sting-less’. These unusual creatures have developed independently of their nearest relatives in the lagoon and have several distinct physical characteristics. Because there are few natural predators in Jellyfish Lake, evolution has eliminated the ‘sting’ jellyfish are noted for, although those who are sensitive to the jellyfish toxins may experience a mild tingle from contact. A simplified explanation of the jellyfish’s behavior is that they are nourished partially by symbiotic algae living in their tissues. The jellyfish migrate daily across the lake, always in a counter-clockwise direction to keep the algae exposed to sunlight and thus keep themselves fed. They also dive down to the poorly-oxygenated lower layers and return to the surface in an effort to provide other nutrients for the algae. Several tour operators lead visitors on snorkeling treks to the island and along the short but rough trail to the lake.

Only snorkeling is allowed; scuba divers’ oxygen bubbles disturb the jellyfish. And, scuba diving in the stratified waters of Jellyfish Lake is dangerous to the diver; oxygen saturation within the water goes only to approximately the 50 foot depth. Below that, the water contains a heavy concentration of hydrogen sulfide which can be absorbed by divers through the skin and cause death. Even while snorkeling, participants are encouraged to float prone in the water and avoid kicking which can damage the fragile creatures. Snorkeling, along with scuba diving, are two of the main attractions of the tiny Republic of Palau. The island nation is blessed with many coral reefs inhabited by diverse colorful fish, several shipwrecks as dive targets, and as much to see underwater as there is above the water line. Most visitors take the time to schedule the boat trip to Jellyfish Lake and enjoy Palau’s other attractions during the rest of their stay.

Koror is both a state within Palau and the largest city. Almost 70% of Palau’s 20,000 citizens live in Koror. The island nation has been under Spanish, German, and Japanese control for much of its recorded history. Japan gained control of the 340 islands that constitute Palau in 1914 under a League of Nations agreement and used it as headquarters for all of Micronesia. After WWII, Palau and Micronesia became trust territories of the United States and declared their independence in 1994. Palau decided not to join the Federated States of Micronesia and maintains its own government. Much evidence of former Japanese occupation remains, and many public buildings and local scenery are reminiscent of Japanese culture. Many of the tour businesses operate in Japanese, and visitors from Japan are common. Enough business is conducted in English that English-speaking visitors from Australia and the United States will find no shortage of tour operators with whom to work.

All types of diving and snorkeling tours are available to visitors. Some tour operators offer live-aboard boats that travel to different dive sites. The atolls, coral reefs, drop-offs and 930 miles of coastlines offer a never-ending undersea landscape awaiting exploration. The area contains the world’s best collection of shipwrecks and downed planes for diving. Helen’s Reef Reserve holds a wealth of marine life. Closer to Koror, Blue Corner’s strong currents attract huge varieties of sea life including reef sharks, wrasses and eagle rays. But that certainly isn’t all that tiny Palau offers.

The City of Koror possesses a number of resorts and hotel lodgings to suit every taste and budget. There are spas, museums, terraced hillsides and jungle vistas awaiting visitors. A jungle river boat tour can be arranged, as can hikes into the heavily forested interior. As a day or two of rain should be expected on every visit to this tropical climate, wise tourists can plan ahead to visit some of the indoor attractions of the islands on days when sunshine is limited.

Some of the must-see attractions to be added to the Jellyfish Lake visit are the museums of Koror. Two in particular detail the history and culture of the native people of these islands. The Belau National Museum offers exhibits of both the ancient past and of Palau’s experiences under occupation and growth under various other nations. Outdoor exhibits showcase such cultural landmarks as taro plots and an authentic men’s meeting hall. The carvings on the men’s meeting hall peaks were the fore-runners of the increasingly popular carved storyboards that tourists may purchase. The stories told on the boards were often legends or recorded events and taught social and moral behavior. One of the best places to purchase storyboards are from the shop at the Koror Jail, where inmates learn the craft from traditional carvers. The Etpison Museum holds a more defined collection of cultural arts and contains a gift shop where visitors often purchase art objects.

The Palau Aquarium is located at the Palau International Coral Reef Center, a great place to observe local ocean fishes up close and learn about coral reefs and their protection. Visitors can learn about dolphins at Dolphins Pacific, where dolphin trainers and divers scuba dive with dolphins. The Center also offers kayak eco-tours of Palau’s native plants and animals.

A visit to Jellyfish Lake encompasses far more than swimming with tiny jellyfish. All of the natural wonders of both the sea and the Pacific islands lie at your fingertips. Even non-divers will thoroughly enjoy this once-in-a-lifetime trip. Come visit the jellyfish at Jellyfish Lake and delight in nature’s diversity.

Things to do at Jellyfish Lake

  • Vacation Rentals
  • Fishing
  • Boating
  • Swimming
  • Kayaking
  • Snorkeling
  • Scuba Diving
  • Hiking
  • Birding
  • Museum

Jellyfish Lake Photo Gallery

Jellyfish Lake Statistics & Helpful Links

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Lake Type: Natural Saltwater Lake, Not Dammed

Surface Area: 14 acres

Shoreline Length: 1 miles

Normal Elevation (Full Pond): 9 feet

Average Depth: 100 feet

Water Volume: 1,377 acre-feet

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Trophic State | LakeLubbers

Trophic State measures the level of algae and nutrients in a lake.

An oligotrophic lake is very clear (blue in color) and does not support much plant or fish life. A hyper-oligotrophic lake is the clearest of all lakes, and is nearly devoid of plants and fish.

A mesotrophic lake is slightly green and supports a moderate degree of plant and fish life. A lake's most desired trophic state is generally this mid-point - the mesotrophic state.

A eutrophic lake is somewhat murky and supports a large amount of plant and fish life. A hypereutrophic lake is clouded with algae, plant life, and fish life. A eutrophic or hyper-eutrophic lake can be difficult to navigate by boat - and is often an unpleasant place to swim.

The use of phosphorus-rich and nitrogen-rich fertilizer on lawns and golf courses surrounding a lake can cause it to become eutrophic or hypereutrophic.


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Catchment or Drainage Area | LakeLubbers

This is the surrounding area that drains into a lake, including land, rivers and their tributaries. This is also known as the lake's "catchment basin".

Small lakes at the highest peaks of mountains have small drainage areas. The world's oceans have the largest drainage areas.


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Lake-Area Population | LakeLubbers

This is the estimated number of people who live in a house with a view of a lake, plus those who self-describe the lake as their home, for example: "I live at Smith Mountain Lake."


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Water Residence Time | LakeLubbers

This is the estimated time that it takes for an amount of water equal to the entire volume of a lake to flow out of - or evaporate from - the lake.

Residence Time can be as short as a few days for fast-flowing small lakes, and can exceed 100 years for slow-flowing large lakes.


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Completion Year | LakeLubbers

This is the year that a reservoir was first filled to the reservoir's normal elevation - or the year that a natural lake was first dammed. A large reservoir can take more than a year to fill after its dam is first closed.

The Grand Anicut in southern India is generally considered the world's oldest dam that still operates. Grand Anicut was constructed in the second century BC. It now impounds an irrigation network that includes roughly one million acres.

You can find many of the the world's newest reservoirs on LakeLubbers. Many of the world's oldest reservoirs appear on the last page of that list.


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Water Volume | LakeLubbers

This is the estimated volume of water that a lake contains -- measured at the lake's normal elevation. By this measure, the world's largest freshwater lake is Siberia's Lake Baikal.

You can find many of the the world's largest lakes (by water volume) on LakeLubbers.

Water Volume can be measured in acre-feet, in cubic miles, or in cubic kilometers. One acre-foot is the amount of water needed to cover one acre (43,560 square feet) to a depth of one foot. One cubic mile equals 3,379,200 acre-feet. One cubic kilometer equals 810,713 acre-feet.

1 acre-foot is equal to 325,851 US gallons. Siberia's Lake Baikal contains about 6,276,367,740,000,000 gallons of freshwater - nearly 1 million gallons for every living person on earth.

The other - and more widely used - measure of a lake's size is the lake's surface acreage. By that measure, the world's largest freshwater lake is North America's Lake Superior.


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Maximum Depth | LakeLubbers

This is the estimated greatest depth of the water in a lake -- measured at the lake's normal elevation. The world's deepest lake is Siberia's Lake Baikal; that lake's maximum depth is estimated at 5,314 feet.

You can find many of the the world's deepest lakes on LakeLubbers. If you select the last page of that list, you will find the (maximum depth of) the shallowest lakes in our database.


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Average Depth | LakeLubbers

This is the estimated average depth of the water in a lake -- measured at the lake's normal elevation. If the water volume and surface area of a lake are known, an estimate of the lake's average depth can be calculated:

Water volume ÷ Surface Area = Average Depth

Example: 1,000,000 acre-feet ÷ 20,000 acres = 50 feet average depth


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Maximum Elevation | LakeLubbers

This is a lake's highest water level, measured by the lake's surface distance above sea level, that can occur during flooding. A lake's highest possible maximum elevation is usually the top of the lake's dam or spillway.

At lakes that include residential development, government regulations usually forbid the construction of homes below a lake's maximum elevation.


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Minimum Elevation | LakeLubbers

This is a lake's lowest water level, measured by the lake's surface distance above sea level, that can be reasonably expected to occur. Low lake levels can occur due to deliberate seasonal draw downs for irrigation or impending snow melt, reduced water inflows, drought and evaporation, residential or commercial water demands, and hydropower generation.

Some lakes' minimum and maximum elevations are virtually the same. Lakes that generate hydropower may vary by several feet - according to power demand. Lakes whose primary purpose is to prevent flooding can seasonally vary by 100 feet or more.

When some lakes reach their minimum elevation, their boat ramps may not be long enough to permit boat access - and boats docked on shallow parts of the lake may end up on dry ground. In those cases, kayakers and shore-based anglers may be among the few happy recreational users of the lake.


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Normal Elevation | LakeLubbers

This is a lake's normal water level, measured by the lake's surface distance above sea level. For a reservoir, this water level is also known as "full pond" or "full pool".

You can find many of the world's highest-elevated lakes on LakeLubbers. Lakes with the lowest elevations (known by LakeLubbers) are shown on the final page of that list.


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Shoreline Length | LakeLubbers

This is the length of the exterior shoreline around a lake - measured at the lake's normal elevation. The shoreline length can be considerably shorter or longer when lake water levels are lower or higher than normal.

A lake with many coves has a much longer shoreline than a lake of similar surface area that is nearly circular in shape.

When known, the shoreline miles that we report in our statistics include only the lake's exterior shoreline, and exclude the shorelines of islands located within a lake's boundaries. In lakes with many islands, those islands' combined shorelines may exceed a lake's exterior shoreline.

You can find many of the world's longest-shoreline lakes on Lakelubbers.


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Surface Area | LakeLubbers

This is the area (acreage, square kilometers, etc.) of the top surface area of a lake - measured at a lake's normal elevation. The surface area can be considerably smaller or larger when lake levels are lower or higher than normal. North America's Lake Superior is the world's largest freshwater lake by this measure.

The other measure of a lake's size is the lake's water volume. By that measure, the world's largest freshwater lake is Lake Baikal in Siberia.

You can find many of the world's largest lakes (acres) on Lakelubbers. There is no widely-accepted minimum surface area that defines a lake. What Lakelubbers describes as a lake, you might call a pond. The smallest lake that Lakelubbers currently includes is Hawaii's 2-acre Lake Waiau.


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Water Level Control | LakeLubbers

This is the organization that controls water releases or outflows from the lake or reservoir. In the USA, this is often the US Army Corps of Engineers, a power company, a municipal water system, an irrigation district, or a paper manufacturing company. In the case of private or gated lakes, a homeowners' association may be the lake's controlling authority.

Many lakes cross borders, including North America's Great Lakes. The control of such lakes and their coveted freshwater may be amicably shared - or hotly disputed.

"Water wars" continue at many lakes as growing populations and crop irrigation needs compete for the freshwater that lakes contain.


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Lake Type | LakeLubbers

There are 3 basic types of lakes that are currently included on LakeLubbers. 2 types may be dammed or not dammed, producing 5 classifications.

- A Reservoir is a man-made freshwater lake that is usually created by damming rivers.

- A Natural Freshwater Lake occurs naturally - often by glacial activity - and has a salinity of less than 30 parts per thousand. It may be dammed to produce electricity or for other reasons.

- A Natural Saltwater Lake occurs naturally and has a salinity of more than 30 parts per thousand (ppt). It may be dammed.

"Brackish" water may be categorized as freshwater or saltwater, depending on its salt content (salinity). Oligohaline water has less than 15 ppt of salt. Mesohaline water has 15-29 ppt. Polyhaline has 30-335 ppt.


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