Andy Rouse / Iceberg and mountain, Svalbard, Norway. Arctic. July.

Chris Mattison / Budgett's Frog (Lepidobatrachus laevis) mostly submerged in muddy water, with eyes visible above water, captive, occurs in South America.

Chris Mattison / Horned frog (Ceratophrys sp) in shallow water, captive occurs in South America.

Juergen Freund / Leatherback turtle (Dermochelys coriacea) hatchlings running to the sea from nest. Jamursbamedi, West Papua, Irian Jaya, Indonesia.

Franco Banfi / Sperm Whale (Physeter macrocephalus) Pico Island, Azores, Portugal, Atlantic Ocean

Richard Herrmann / Research submersible submerging to explore hot vents, Danzante Island, Baja California, Mexico

Felis Images / Bengal tiger (Panthera tigris) standing in water. Bandhavgarh National Park, Madhya Pradesh, India. Photo Phillip Ross/Felis Images

Sandesh Kadur / Bengal tiger (Panthera tigris) submerged in water. Ranthambore National Park, India.

David Tipling / Samphire (Salicornia sp) in saltmarsh. Holkham National Nature Reserve, North Norfolk, England, UK. October.

Mark Carwardine / Aerial view of four Humpback whales (Megaptera novaeangliae) at surface, blowing then submerging, Gorda Banks, Baja California, Mexico, 2017.

Frederique Olivier / Group of Southern rockhopper penguins (Eudyptes chrysocome) waiting to dive into the sea, washed away by a large wave, New Island, Falkland Islands.

Frederique Olivier / Hippopotamus (Hippopotamus amphibius) at surface, closes its nostrils and submerging, Serengeti NP, Tanzania.