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

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

Roy Mangersnes / Harbour seal (Phoca vitulina) resting on submerged rock, west coast of Spitsbergen, Svalbard, Norway, June.

Nick Upton / Juvenile grey heron (Ardea cinerea) standing on submerged drainage pipe holding young Perch (Percia fluviatilis) it has just caught, St.James's Park, London, UK, September.

Franco Banfi / Remains of submerged mill, Lago di Capo D'Acqua, Capestrano, Aquila, Abruzzo, Italy, May 2006.

Franco Banfi / Remains of submerged mill, Lago di Capo D'Acqua, Capestrano, Aquila, Abruzzo, Italy, May 2006.

Franco Banfi / Scuba diver with remains of submerged mill, Lago di Capo D'Acqua, Capestrano, Aquila, Abruzzo, Italy, May 2006.

Franco Banfi / Scuba diver swimming over remains of submerged mill, Lago di Capo D'Acqua, Capestrano, Aquila, Abruzzo, Italy, May 2006.

Franco Banfi / Partly submerged ruins viewed through Snell's window, Lago di Capo D'Acqua, Capestrano, Aquila, Abruzzo, Italy, May 2006.

Franco Banfi / Partly submerged ruins, Lago di Capo D'Acqua, Capestrano, Aquila, Abruzzo, Italy, May 2006.

Anup Shah / Hippopotamus group submerged in lily covered pool (Hippopotamus amphibius). Maasai Mara National Reserve, Kenya.

Anup Shah / Hippopotamus group submerged in lily covered pool (Hippopotamus amphibius). Maasai Mara National Reserve, Kenya.

Anup Shah / Hippopotamus (Hippopotamus amphibius) group submerged in water lettuce covered pool. Maasai Mara National Reserve, Kenya.

Anup Shah / Hippopotamus group submerged in lily covered pool (Hippopotamus amphibius). Maasai Mara National Reserve, Kenya.

Anup Shah / Hippopotamus group submerged in lily covered pool (Hippopotamus amphibius). Maasai Mara National Reserve, Kenya.

Jan Hamrsky / Freshwater hydra (Hydra viridis) attached to submerged wood, Europe, February, controlled conditions.

Jan Hamrsky / Minnow mayfly (Baetidae) nymph on submerged twig, Europe, January, controlled conditions.

Alex Hyde / 50 mile an hour road sign submerged in huge snow drifts on country roads in the Peak District National Park, Deryshire, UK. March.

Ben Cranke / Polar Bear (Ursus maritimus) diving underwater to feed of a submerged whale carcass, Svalbard, Norway. July.

Ben Cranke / Polar Bear (Ursus maritimus) diving underwater to feed of a submerged whale carcass, Svalbard, Norway. July.

Anup Shah / Hippopotamus (Hippopotamus amphibius) group submerged in water.Maasai Mara National Reserve, Kenya. Feb 2012.

Anup Shah / Hippopotamus (Hippopotamus amphibius) head part submerged in water.Maasai Mara National Reserve, Kenya. Feb 2012.

Charlie Summers / Mallard (Anas platyrhynchos) pair mating in city park pond, female almost completely submerged, Reykjavik, Iceland, May.

Markus Varesvuo / Female Shoveler (Anas clypeata) standing on partically submerged rock, Loviisa, Finland, June

Markus Varesvuo / Male Shoveler (Anas clypeata) on water with head submerged, dabbling for plant food, Loviisa, Finland, June

Markus Varesvuo / Teal (Anas crecca) female feeding on water with head partially submerged, Loviisa, Finland

Will Burrard-Lucas / Hippopotamus (Hippopotamus amphibius) mother and calf submerged in water, South Luangwa National Park, Zambia. January.

Guy Edwardes / 2020VISION / Submerged weeds in the River Test, near Longstock, Hampshire, England, UK, May.

Guy Edwardes / 2020VISION / Submerged weeds in the River Test, near Longstock, Hampshire, England, UK, May.

Guy Edwardes / 2020VISION / Submerged weeds in the River Test, near Longstock, Hampshire, England, UK, May.

Guy Edwardes / 2020VISION / Submerged weeds in the River Test, near Longstock, Hampshire, England, UK, May.

Daniel Heuclin / Amazonian horned frog (Ceratophrys cornuta) partially submerged in water, French Guiana.

Luciano Candisani / Jacare Caiman (Caiman yacare) pair in flooded field, rainy season, Pantanal, Brazil

Anup Shah / Japanese Macaque (Macaca fuscata) female and baby submerged in thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Anup Shah / Japanese Macaque (Macaca fuscata) male submerged in thermal hotspring pool. Jigokudani Yaen-Koen National Park, Japan, February.

Anup Shah / Japanese Macaque (Macaca fuscata) female and baby submerged in thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Anup Shah / Japanese Macaques (Macaca fuscata) grooming while submerged in thermal hotspring pool. Jigokudani Yaen-Koen National Park, Japan, February.

Anup Shah / Japanese Macaque (Macaca fuscata) baby grooming its mother while submerged in thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Anup Shah / Japanese Macaques (Macaca fuscata) submerged in thermal hotspring pool. Jigokudani Yaen-Koen National Park, Japan, February.

Anup Shah / Japanese Macaque (Macaca fuscata) baby screaming while submerged in thermal hotspring pool. Jigokudani Yaen-Koen National Park, Japan, February.

Anup Shah / Japanese Macaque (Macaca fuscata) female and baby submerged in thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Fiona Rogers / Japanese Macaque (Macaca fuscata) baby submerged in a thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Fiona Rogers / Japanese Macaque (Macaca fuscata) baby submerged in a thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Fiona Rogers / Japanese Macaque (Macaca fuscata) baby submerged in a thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Fiona Rogers / Japanese Macaque (Macaca fuscata) female with suckling baby submerged in a thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Fiona Rogers / Japanese Macaque (Macaca fuscata) female submerged in a thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Lou Coetzer / Reed cormorant (Microcarbo africanus) sitting on partially submerged Hippopotamus (Hippopotamus amphibius) Chobe River, Botswana, May, Vulnerable species.

Wild Wonders of Europe / Lundgren / Submerged Water soldier / Water pineapple plant (Statiotes aloides) small lake in Danube Delta, Romania, June.

Wild Wonders of Europe / Lundgren / Submerged Water soldier / Water pineapple plant (Statiotes aloides) small lake in Danube Delta, Romania, June.

Wild Wonders of Europe / Lundgren / Partly submerged Water soldier / Water pineapple (Statiotes aloides) in a small lake in Danube Delta, Romania, June.

Eric Medard / Yellow-spotted salamander (Salamandra salamandra) half submerged in water, taken at night using infra-red remote camera trap, France, November.

Mark Taylor / Car park flooded by River Wey, with cars almost completely submerged during Christmas 2013 flooding, Guildford. Surrey, England, UK. 25th December 2013.

Steven Kazlowski / Young polar bear (Ursus maritimus) submerged, swimming in slushy icy water, off the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Beaufort Sea, Alaska, October.

Steven Kazlowski / Polar bear (Ursus maritimus) subadult submerged in slushy icy water, off Bernard Spit and the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Beaufort Sea, Alaska, O...

David Woodfall / Bird feeders in garden almost submerged during February 2014 floods, Upton upon Severn, Worcestershire, England, UK, 8th February 2014.

David Woodfall / Bird feeders in garden almost submerged during February 2014 floods, Upton upon Severn, Worcestershire, England, UK, 8th February 2014.

David Woodfall / Submerged garden during February 2014 flooding, Upton upon Severn, Worcestershire, England, UK. 8th February 2014.

David Woodfall / Boat in flood tethered to apple tree in garden submerged by February 2014 flooding, Upton upon Severn, Worcestershire, England, UK, 8th February 2014.

David Woodfall / Boat in flood tethered to apple tree in garden submerged by February 2014 flooding, Upton upon Severn, Worcestershire, England, UK, 8th February 2014.

Nick Upton / Toothed wrack (Fucus serratus) on rocks exposed at low tide and submerged in a rockpool, Lyme Regis, Dorset, UK, May.

Tim Fitzharris / American Alligator (Alligator mississippiensis) with a butterfly on its snout, Everglades National Park, Florida

Alex Mustard / Male largemouth bass (Micropterus salmoides) guards his fry (too small to be visible) as they shelter amongst the roots of a tree submerged in a river. Rainbow River, Florida, United States of America...

Laurent Geslin / Grey Heron (Ardea cincerea) with head partially submerged in lake, Regent's Park, London, England

Franco Banfi / Wreck of airplane B-24 Liberator, Vis Island, Croatia, Adriatic Sea, Mediterranean

Franco Banfi / Wreck of airplane B-24 Liberator, Vis Island, Croatia, Adriatic Sea, Mediterranean

Franco Banfi / Scuba diver exploring the wreck of aeroplane 'B-24 Liberator' Vis Island, Croatia, Adriatic Sea, Mediterranean

Franco Banfi / Scuba diver exploring the wreck of aeroplane 'B-24 Liberator' Vis Island, Croatia, Adriatic Sea, Mediterranean

Pete Oxford / African Forest Elephant (Loxodonta africana cyclotis) crossing river, Lekoli River, Democratic Republic of the Congo

Winfried Wisniewski / African Elephant (Loxodonta africana) group using trunks as snorkels while submerged in Chobe River, Chobe National Park, Botswana

Nick Garbutt / Yacare Caiman (Caiman yacare) resting submerged at the edge of the Piquiri River, northern Pantanal, Brazil.

Roland Seitre / Long-tailed Macaque (Macaca fascicularis) hunting for invertebrates underwater, southeast Asia

Roland Seitre / Long-tailed Macaque (Macaca fascicularis) pair hunting for invertebrates underwater, southeast Asia

Roland Seitre / Long-tailed Macaque (Macaca fascicularis) pair hunting for invertebrates underwater, southeast Asia

Nick Upton / Pair of Mute swans (Cygnus olor) swimming near submerged gateway on flooded pastureland on the Somerset Levels after weeks of rain, Southlake moor, Burrowbridge, UK, January 2013.

Nick Upton / Trees and bushes fringing the River Avon partly submerged after weeks of heavy rain caused it to burst its banks, Lacock, Wiltshire, UK, January 2013.

Nick Upton / Trees fringing the River Avon partly submerged after weeks of heavy rain caused it to burst its banks, Lacock, Wiltshire, UK, January 2013.

Nick Upton / Trees fringing the River Avon partly submerged after weeks of heavy rain caused it to burst its banks, Lacock, Wiltshire, UK, January 2013.

Richard Du Toit / African Elephant (Loxodonta africana) totally submerged underwater with just tip of trunk above water, Limpopo Province, Kruger National Park, South Africa

Wild Wonders of Europe / Widstrand / White Spoonbills (Platalea leucorodia) resting on half submerged tree, Danube delta rewilding area, Romania May

David Pattyn / Coot (Fulica atra) pair mating, the female often is almost completely submerged, you can only see small part of her back here, La Dombes lake area, France, April

Marie Read / Wilson's Phalaropes (Phalaropus tricolor), flock resting on partly-submerged tufa formation Mono Lake, California, USA, July.

Christophe Courteau / Hippopotamus yawning {Hippopotamus amphibius}. Moremi GR Okavango Delta, Btswn.

Mike Potts / Grey Seal (Halichoerus grypus) resting on submerged rocks. Bardsey Island, North Wales, UK, August

Mike Potts / Grey Seals (Halichoerus grypus) resting on submerged rocks. Bardsey Island, North Wales, UK, August

David Pattyn / Great Crested grebe (Podiceps cristatus) male dancing on top of the female after mating, she is submerged, La Dombes area, France, June

David Pattyn / Great Crested grebe (Podiceps cristatus) male dancing on top of the female after mating, she is submerged, La Dombes area, France, June

Nick Upton / Three Painted top shells (Calliostoma zizyphinum) on submerged rocks encrusted with red algae low on the shore, Wembury, Devon, UK, August.

Nick Upton / Common brittle star (Ophiothrix fragilis) well camouflaged among mix of red and green algae including Coralweed (Corallina officinalis), Harpoon weed (Asparagopsis armata) and Sea lettuce (Ulva lactuc...

Nick Upton / Cushion star (Asterina gibbosa) on the move over submerged rocks low on the shore among a mix of red algae including Coralweed (Corallina officinalis) and Sea horsetail (Halurus equisetifolus) submerg...

Nick Upton / Three Common limpets (Patella vulgata) on the move on intertidal rock submerged at mid tide, Falmouth, Cornwall, UK, August.

Nick Upton / Submerged Star ascidian colony (Botryllus schlosseri) attached to boulder in a rockpool, Helford River, Cornwall, UK, August.

Nick Upton / Toothed / Serrated wrack (Fucus serratus) submerged at mid tide, near Falmouth, Cornwall, UK, August.

Nick Upton / Red tube worm (Serpula vermicularis) attached to submerged rock with patches of encrusting red algae low on the shore, near Falmouth, Cornwall, UK, August.

Paul Williams / Yacare caiman (Caiman yacare) basking on submerged trunk in river, Pantanal, Pocone, Brazil

Nick Upton / Flat periwinkle (Littorina obtusata / Littorina littoralis) on Toothed wrack (Fucus serratus) submerged at mid tide, near Falmouth, Cornwall, UK, August.

Eric Baccega / Red-eared slider / turtle basking on submerged branch (Trachemys scripta elegans) captive, Alsace, France