Steven Kazlowski / Two curious young Polar bears (Ursus maritimus), Barter Island, off the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Doug Perrine / Bryde's whale {Balaenoptera brydei / edeni} with throat pleats expanded after feeding on baitball of Sardines {Sardinops sagax} off Baja California, Mexico, Eastern Pacific Ocean. Veolia Environnement...

Alex Mustard / Dugong (Dugong dugon) male and juvenile Golden trevally (Gnathanodon speciosus) swimming over Seagrass (Halophila stipulacea) meadow. Marsa Nabaa, Marsa Alam, Egypt.

Alex Mustard / Oceanic whitetip shark (Carcharhinus longimanus) swimming close to surface. Brothers Islands, Egypt.

Shane Gross / Caribbean reef shark (Carcharhinus perezi), two from below, one close up. Caribbean Sea off Gardens of the Queen National Park, Cuba.

Jordi Chias / Leopard seal (Hydrurga leptonyx) resting over an iceberg, Antarctic Peninsula, Antarctica.

Jordi Chias / Iceberg, Antarctic Peninsula, Antarctica.

Franco Banfi / Diver exploring an iceberg in Greenland Sea. Tasiilaq, East Greenland. April 2018.

Franco Banfi / Sugar kelp (Saccharina latissima) near iceberg, view upwards to gap in sea ice. Tasiilaq, East Greenland. April.

Shane Gross / Lemon shark pup (Negaprion brevirostris) in mangrove forest which acts as a nursery for juveniles of this species. Eleuthera, Bahamas.

David Fleetham / Silhouette of a Green Sea Turtle (Chelonia mydas) passes overhead. West Maui, Hawaii.

David Fleetham / Schooling Lemon / Milletseed butterflyfish (Chaetodon miliaris) below kayakers off Maui, Hawaii.