Maly Semyachik is a stratovolcano located in the eastern part of Kamchatka Peninsula, Russia. A hot, acidic crater lake fills the historically active Troitsky Crater, which formed during a large explosive eruption about 400 years ago. The water in the lake has an unusual bright turquoise color. It’s because the waters of the lake are poisonous due to the content of several types of acids and other chemical compounds.The water in the lake never freezes, even when everything is covered with a layer of ice and deep snow.
info source: wikipedia
By zarmel http://www.geodiversite.net/auteur2 – http://www.geodiversite.net/media191, CC BY-SA 3.0, Link
The peak of the volcano Maly Semyachik – By Photo by Dan Miller, 1990 (U.S. Geological Survey). – http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-14=&volpage=photos, Public Domain, Link
View of the volcano – By Photo by Dan Miller, 1990 (U.S. Geological Survey). – http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-14=&volpage=photos, Public Domain, Link
By Photo by Dan Miller, 1990 (U.S. Geological Survey). – http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-14=&volpage=photos, Public Domain, Link
By BohunkaNika – Own work, CC BY-SA 4.0, Link