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Meromictic Lake at Penang National Park

I only heard about the meromictic lake after a visit to Penang National Park.

Nurul Azura being filmed by RTM at Meromictic Lake at Penang National Park
Nurul Azura being filmed by RTM

Nurul Azura, the deputy superintendent for the park, gave us a short explanation about this phenomenon. It truly is amazing, as the position of the river mouth, the natural flow of the monsoon wind, the sea current and also the placement of the boulders at the river mouth make it possible.

If any of these elements were artificially changed, we will no longer have this natural formation anymore. Talk about the real natural heritage. Wow!

I took the advantage of the trip to listen carefully to the explanation because it really interested me. I traveled with the RTM TV crew who recorded Nurul Azura's explanation on video tape.

Meromictic describes a condition whereby two layers of liquids of different densities, in this case, the salty sea water and fresh clear water from rain and five small rivers, remain separated. Usually at a river mouth or a delta, both kinds of water will mingle, creating diluted sea water.

Here, the salty sea water, being more dense will remain at the lower layer while the less dense fresh water will remain on top. In terms of temperature also, the sea water remains warm while the fresh water remains cool. Further, since the lower part of the lake lacks oxygen, not many animals can live in there to stir up the two levels of water. Isn't it amazing?

Curious visitors reading the explanation about the lake
Curious visitors reading the explanation about the lake

How do we know for sure? The scientist at USM have been studying this lake for many years and they have confirmed that this lake is a natural meromictic lake, by confirming the salinity at different depths, and also examining the type of organisms that live in this lake.

Aerial view of the lake
Aerial view of the lake.

You should know that another example of "true" meromictic lake is the world famous Dead Sea. However, the Dead Sea is a permanent lake, not a seasonal one like here. In total, there are less than 20 real meromictic lakes in the whole world. This is another reason why this area deserves to be part of Penang National Park.

The way the lake is formed is also truly amazing. It only happens during the change of monsoon, normally in April-Mei and also in October-November, the rest of the year it is dry, resembling a Savannah-like environment to the naked eye. The truth is, even when it is dry, plenty of anaerobic micro-organisms survive there. Hardy grass grows at the bottom of the lake. There are a few scattered boulders too in the lake, which were not there before the tsunami hit the area in 2004.

The signboard marking the location of the lake.

Five small rivers flow into the lake which measures 2.77 square kilometers. At the lake, a natural dam would form by the action of the sea current and the changing monsoon wind pushing the sand into a dike at the river mouth. The strategic presence of a few boulders here also made this natural dam to be possible.

Strange enough, after its session is complete, the dam would break naturally and the water of the lake will flow back into the sea. At this time, visitors would have to be very careful if they are swimming or playing in the lake, because the rush of the current is very strong and they could be sucked out into the open sea.

	gazebo to enjoy the scenery
A gazebo built for you to rest and enjoy the scenery
at the edge of the meromictic lake.

The depth of the lake can reach up to three meters. Its depth will vary, even during the supposedly "full" period. So it depends also on your luck if your visit to this lake coincides with the time when the lake is filled with water. When the water drains out, the bottom is soggy with mud. In dry season though, it is perfectly alright to walk on the surface when the mud hardens and the lake becomes a mud plain.

This natural phenomenon is worthy to be published in any of National Geographics productions. Like I said before, we should be proud to have this natural formation in our own backyard. Check out the map of Penang National Park to know the location of this lake.

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