Morskie Oko lake, in Tatra mountains, Poland.
(<a href="//commons.wikimedia.org/wiki/User:Bakko" title="User:Bakko">Felipe Crespo Lombardía</a>)
CC BY-SA 3.0
Own work. Photo taken by (<a href="//commons.wikimedia.org/wiki/User:Bakko" title="User:Bakko">Felipe Crespo Lombardía</a>)