Bryan and Cherry Alexander / Chinstrap penguins (Pygoscelis antarcticus) and Snowy sheathbill (Chionis alba) on snowy rocks. Half Moon Island, South Shetland Islands, Antarctica, October.

Bryan and Cherry Alexander / Chinstrap penguins (Pygoscelis antarcticus) on snowy rocks. Half Moon Island, South Shetland Islands, Antarctica, October.

Nick Garbutt / Chin-strap Penguin (Pygoscelis antarcticus) displaying. Half-Moon Island, South Shetland Islands, Antarctica. February. (digitally stitched image)

Michel Roggo / Waves crashing in front of bow of MV Ortelius, Beaufort 9, near Half Moon Island, South Shetland Islands, Antarctic Peninsula, Antarctica. January 2017.Photographed for The Freshwater Project

Sylvain Cordier / Chinstrap penguins (Pygoscelis antarcticus), mating, Half Moon Island, Antarctic Peninsula

Sylvain Cordier / Adelie penguins (Pygoscelis adeliae), pair mating, Half Moon Island, Antarctic Peninsula

Sylvain Cordier / Chinstrap penguin (Pygoscelis antarcticus) on nest with egg, Half Moon island, Antarctic Peninsula

Sylvain Cordier / Adelie penguin (Pygoscelis adeliae), chick, Half Moon island, Antarctic Peninsula

Sylvain Cordier / Chinstrap penguin (Pygoscelis antarcticus), walking, Half Moon Island, Antarctic Peninsula

Sylvain Cordier / Chinstrap Penguin (Pygoscelis antarcticus) at nest with one egg, Half Moon island, Antarctic Peninsula

Tim Laman / Zodiac boat carrying tourists back to the expedition ship 'National Geographic Explorer' over a rough sea in the bay of Half Moon Island, South Shetland Islands group, Antarctica, February 2011.

Tim Laman / Lichen on rock, Half Moon Island, South Shetland Islands group, Antarctica.