Crystal clear waters of <a href="//commons.wikimedia.org/wiki/Achensee" title="Achensee">Achen Lake</a> in Austria, as seen from Pertisau. Mountain reflection of Klobenjoch.
<a href="//commons.wikimedia.org/wiki/User:ArticCynda" title="User:ArticCynda">ArticCynda</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>