Methane bubbles in the icy surface of Silsersee with snowy peak illuminated by sunset light, Lake Sils, Engadine Valley, canton of Graubunden, Switzerland, Europe

Common frog (Rana temporaria) in spawning pond, Northumberland, England, United Kingdom, Europe

Methane and air bubbles caught in the ice when the lake froze, Lake Baikal, Russia.

A scuba diver swims through an underwater field of tape grass leading away from the Blue Springs cave in Merritts Mill Pond in Marianna, Florida.

Frozen Riffelsee lake by Matterhorn in Switzerland, Europe

Frozen Riffelsee lake by Matterhorn in Switzerland, Europe

Frozen Riffelsee lake by Matterhorn at sunset in Switzerland, Europe

Ice bubbles trapped in frozen Lake Sils at sunset with Piz Da La Margna in background, Engadine, Graubunden canton, Switzerland, Europe

Ice bubbles trapped in Lake Sils with Piz Da La Margna in background at dawn, Engadine, Graubunden canton, Switzerland, Europe

Clouds in the burning sky at sunset on Piz Da La Margna and ice bubbles trapped in Lake Sils, Engadine, Graubunden, Switzerland, Europe

Frozen Lake Andossi in Spluga Valley, Italy, Europe

Frozen Lake Andossi in Spluga Valley, Italy, Europe

Close-up of granite rocks in a pond, Bubble Pond, Acadia National Park, Maine, USA

Reflection of stones in water, Bubble Pond, Acadia National Park, Maine, New England, USA