The lake was formed by natural causes. The fact that the lake flow into two streams. As part of a river a huge amount of iron salts, and in the other – all sorts of organic compounds, borrowed from the peatland located near in the valley. Merging into a lake two rivers, streams react chemically with each other, in which the ink and can be obtained.
Of course, in this lake is completely absent any flora and fauna, as the ink is toxic to all living things. Swim, of course, it is also forbidden – it is dangerous to health, and then wash off the ink is not very fun.