Tuesday, June 18, 2013

The clearest lake in the world

Ngati Apa, also known as Blue Lake, has been found by the New Zealand National Institute of Water and Atmospheric Research to have the clearest water on Earth. With a visibility measured at 76 metres, it is very close to the 80 metres of optically pure distilled water. Situated at 1200 M above sea level, near Nelson at the north end of South Island, its water flows down from Lake Constance higher up, being filtered on its way through by a glacial moraine (depicted in the picture). This moraine also forms a dam between the lakes.

The lake is sacred to the Maori, and the local tribe was consulted before the dive where this photo was taken. Its clarity is partly due to being above the tree line, keeping the water free from runoff from foliage. Small floods sometimes affect its purity for a short while, before its usual state reasserts itself.

Image credit: Klaus Thymann /Project Pressure.



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