The lake formed around 14,000 years ago as a result of glacial retreat, which left a depression in the ground that inevitably filled with water. The water contained within the lake its brown in colour, accredited to the presence of leached organic matter from the surrounding forest. The brown colouring creates the ideal conditions to reflect the perfectly positioned mountains to the east.
Image and more information, here: http://
Check out our previous post on Mount Cook: http://on.fb.me/WprwX3