David Fleetham / False killer whale (Pseudorca crassidens) just below surface exhaling as it breaks the surface. Maui, Hawaii.

David Fleetham / Great white shark (Carcharodon carcharias) with mouth open, just below the surface off Guadalupe Island, Mexico.

Franco Banfi / Sperm whale (Physeter macrocephalus) tail below water as whale surfaces, Dominica, Caribbean Sea, Atlantic Ocean, Vulnerable species.

Franco Banfi / Sperm whale (Physeter macrocephalus) mother surfacing with calf below, Dominica, Caribbean Sea, Atlantic Ocean, Vulnerable species.

Michel Roggo / Autumn trees viewed from below Lake Baikal, Lake Baikal UNESCO World Heritage Site, Siberia, Russia. May 2013. Photographed for The Freshwater Project.

Ross Hoddinott / Foam on beach below cliffs at Burton Bradstock, late evening light, Dorset, UK. November 2016.

Ingo Arndt / Foot of Banded snail {Cepaea sp} viewed from below

Richard Robinson / Shortfin mako shark (Isurus oxyrinchus) head on just below surface, another in background, off the West Coast of Auckland, New Zealand, February

Richard Robinson / Shortfin mako shark (Isurus oxyrinchus) profile portrait, just below surface, off the West Coast of Auckland, New Zealand, February

Lucas Bustamante / Sarayacu clownfrog (Dendropsophus sarayacuensis) with its clutch of eggs developing and starting to drop off from a leaf into the water below, where the tadpoles will develop. Sumaco National Park, N...

Tony Wu / Humpback whale (Megaptera novaeangliae), fluke of female with male calf playing below, Vava'u, Tonga, Pacific Ocean.

Floris van Breugel / Temple Crag above Second lake, one the of the Big Pine lakes below the Palisade basin, John Muir Wilderness, Sierra Nevada, California, USA, May