Tui De Roy / Snares Crested penguin (Eudyptes robustus) bathing in freshwater pool, Snares Island, New Zealand Sub-Antarctic Islands. Endemic and vulnerable species.

Wild Wonders of Europe / Lundgren / Pool Frog (Pelophylax lessonae) viewed from below while swimming, underwater around Crisan village, Danube Delta, Romania, June.

Wild Wonders of Europe / Lundgren / Pool frog (Pelophylax lessonae) reflected in waters surface at night, Danube Delta, Romania, June.

Graham Eaton,Graham Eaton / A boy swimming crawl stroke in a pool, Egypt, September 2012. Model released

Steven Kazlowski / Polar bear (Ursus maritimus) underwater view swimming in a pool, Anchorage Zoo, Alaska, USA. No release available.

Cheryl-Samantha Owen / Cape gannet (Morus capensis) coated in oil swimming in pool at the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB). Vulnerable species. Third place in Mankind and Nature p...

Cheryl-Samantha Owen / Cape gannet (Morus capensis) coated in oil swimming in pool at Southern African Foundation for the Conservation of Coastal Birds (SANCCOB). Vulnerable species. Third place in Mankind and Nature portf...

Cheryl-Samantha Owen / Cape gannet (Morus capensis) coated in oil swimming in pool at the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB). Cape Town, South Africa. Vulnerable species. Third place...

MYN / Piotr Naskrecki / Red spotted / Eastern Newts (Notophthalmus viridescens) swimming; from a vernal pool, Woburn, Massachusetts, USA, April, digital composite. meetyourneighbours.net project

Alex Mustard / A young California sealion (Zalophus californianus) swims in a shallow pool. Los Isotes, La Paz, Mexico. Sea of Cortez, East Pacific Ocean.

Wild Wonders of Europe / Roggo / Alpine newt (Triturus alpestris) chasing a ball of Water fleas in a gravel pit pool, Fribourg, Switzerland, June 2009

Juergen Freund / Fern Pool - a permanent swimming hole surrounded by lush vegetation, Karajini National Park, Western Australia

Steven David Miller / Infinity pool overlooking Lake Argyle. The Kimberley, Western Australia. 2017.

Nick Upton / Velvet swimming crab (Necora puber) in a rock pool, hiding among Coralweed (Corallina officinalis), Cornwall, UK, March.

Nick Upton / Common shore crab (Carcinus maenas) hiding among Coralweed (Corallina officinalis) in a rock pool, Cornwall, UK, March.

Mike Read / Eurasian wigeon (Anas penelope) pair on pool. Greylake Nature Reserve, near Othery, Somerset Levels, England, UK. February.

Mike Read / Common teal (Anas crecca) female swimming in pool. Greylake Nature Reserve, near Othery, Somerset, England, UK. February.

Mike Read / Common snipe (Gallinago gallinago) swimming in pool. Greylake Nature Reserve, near Othery, Somerset, England, UK. February.

Juan Manuel Borrero / People bathing in pool at base of waterfall. Natural Monument of Caldeira Velha, Ribeira Grande, Sao Miguel Island, Azores, Portugal. 2019.

Juan Manuel Borrero / Swimming pool at base of waterfall. Natural Monument of Caldeira Velha, Ribeira Grande, Sao Miguel Island, Azores, Portugal. 2019.

Nick Upton / Close-up of a Common shore crab (Carcinus maenas) in a rock pool, vibrating its maxillae to aerate its gills and flicking its antennae, Cornwall, UK, March.

Nick Upton / Close-up of a Common shore crab (Carcinus maenas) in a rock pool, vibrating its maxillae to aerate its gills and flicking its antennae, Cornwall, UK, March.

SCOTLAND: The Big Picture / Grey seal (Halichoerus grypus) pup playing in a freshwater pool with a piece of plastic, Orkney Isles, Scotland

SCOTLAND: The Big Picture / Grey seal (Halichoerus grypus) pup playing in a freshwater pool with a piece of plastic, Orkney Isles, Scotland, UK, April.

Steven David Miller / People swimming in freshwater pools on Waterfall Creek, at the top of Gunlom Falls. Mary River, Kakadu National Park, Northern Territory, Australia. March 2014.

Ashley Cooper / Solar panels on a house roof in Sivota, Greece. June 2014

Ashley Cooper / A swimming pool at a holiday complex in Skala Eresou on Lesvos, Greece. June 2013

Tony Heald / Hippopotamus (Hippopotamus amphibius) in water at sunset. Mana Pools National Park, Zimbabwe.

David Fleetham / Two divers practices their diving skills in a resort pool, Hawaii. December 2013. Model released.

David Fleetham / A woman lies at the edge of an infinity pool with a tropical background. Curacao, Netherlands Antilles, Caribbean, May.

David Fleetham / Aerial view of woman swimming in pool in Guangzhou, China.

David Fleetham / Aerial view of woman swimming in pool in Guangzhou, China.

David Fleetham / Split-level image of swimming pool and ship / restaurant named The S/V Mnuw (Sea Hawk) at the Manta Ray Bay Hotel on the island of Yap, Micronesia. September 2007.

Michel Roggo / North American Beaver (Castor canadensis), urinating whilst swimming in the pool around his lodge, Northern Rockies, British Columbia, Canada July. Photographed for The Freshwater Project

Tui De Roy / Marine Iguana (Amblyrhynchus cristatus) swimming in coastal pool, Tortuga Bay, Santa Cruz Island, Galapagos Islands, Ecuador

Angelo Gandolfi / Woman bathing in pool of Rio Claro river. Corcovado National Park UNESCO World Heritage Site, Osa peninsula, Costa Rica

Steve Downer / Two Mallard (Anas platyrhynchos) drakes swimming in Womere Pool, Cannock Chase AONB, Staffodshire, England, UK, April.

Steve Downer / Mute swans (Cygnus olor) swimming a pool, Birmingham, England, UK, February.

SCOTLAND: The Big Picture / Red throated diver (Gavia stellata) and chicks swimming in a moorland pool, Sutherland, Scotland, UK, June.

Nick Upton / Velvet swimming crab (Necora puber) in a rock pool, waving and opening one of its claws in a threat display, Cornwall, England, UK, September.

Nick Upton / Velvet swimming crab (Necora puber) moving off, leaves frame, Cornwall, England, UK, September.

Nick Upton / Common prawns (Palaemon serratus) feeding on a dead Montagu's crab (Xantho hydrophilus) in a rockpool, with a a Rock goby (Gobius paganellus) swimming past, Cornwall, England, UK, September.

Nick Upton / Montagu's crab (Xantho hydrophilus) in a rockpool, showing threat posture with open claws raised, walks out of frame, Cornwall, England, UK, September.

Nick Upton / Two Montagu's crabs (Xantho hydrophilus) competing for a crevice to hide in within a rockpool, with a young Velvet swimming crab (Necora puber) moving away nearby, Cornwall, England, UK, September.

Tui De Roy / Snares-crested penguin ( Eudyptes robustus) bathing in rain pool at end of moult. Snares Island, New Zealand Sub-Antarctic Islands.

Nick Upton / Shelduck drake (Tadorna tadorna) preening in a marshland pool, with a foraging Coot (Fulica atra) and a female Shelduck swimming past, Gloucestershire, England, UK, March.

Nick Upton / Two Mallard (Anas platyrhychos) drakes preening and one dabbling in a marshland pool among dense sedge beds, Gloucestershire, England, UK, May.

Nick Upton / Three Mallard (Anas platyrhychos) drakes dabbling in a marshland pool among dense sedge beds, Gloucestershire, England, UK, May.

Nick Upton / Two Mallard (Anas platyrhychos) drakes swimming in a marshland pool among dense sedge beds, Gloucestershire, England, UK, May.

Nick Upton / Pintail (Anas acuta) resting and Common teal (Anas crecca) swimming in a marshland pool in heavy rain, Gloucestershire, England, UK, February.

Nick Upton / Greylag goose (Anser anser) foraging on the edge of a marshland pool, with another individual swimming in the background, Gloucestershire, England, UK, January.

David Pattyn / Coconut palm (Cocos nucifera) trees reflected in pool of hotel with sea beyond, Anjajavy Private Reserve, north west Madagascar, September 2016.

SCOTLAND: The Big Picture / Tufted duck (Aythya fuligula) drake on breeding pool, St John's Pool Bird Reserve, Thurso, Caithness, Scotland, UK, May.

SCOTLAND: The Big Picture / Tufted duck (Aythya fuligula) drake calling, St John's Pool Bird Reserve, Thurso, Caithness, Scotland, UK, May.

SCOTLAND: The Big Picture / Tufted duck (Aythya fuligula) drake swimming, St John's Pool Bird Reserve, Thurso, Caithness, Scotland, UK, May.

Graham Eaton / Grey heron (Ardea cinerea) standing at rim of infinity pool, Maldives, Indian Ocean, January 2017.

Alex Hyde / Male Alpine Newt (Ichthyosaura / Triturus alpestris) in mountain pool. Nordtirol, Austrian Alps. June.

David Pattyn / Cattle egret (Bubulcus ibis) at the edge of swimming pool in a tourist resort, Gambia, Africa, May.

David Pattyn / Cattle egret (Bubulcus ibis) at the edge of a swimming pool in a tourist resort, Gambia, Africa, May.

David Pattyn / Western red colobus (Procolobus badius) at the edge of swimming pool in a tourist resort, Gambia, Africa, May.

David Pattyn / Western red colobus (Procolobus badius) at the edge of a swimming pool in a tourist resort, Gambia, Africa, May.

Laurent Geslin / Northern bat (Eptesicus nilssoni) flying over swimming pool, Switzerland, June.

Cyril Ruoso / Children in swimming pool racing in Japanese giant salamander (Andrias japonicus) costume, in Salamander Festival, Yubara, Honshu, Japan, August.

Cyril Ruoso / Children in swimming pool racing in Japanese giant salamander (Andrias japonicus) costume, in Salamander Festival, Yubara, Honshu, Japan, August.

Cyril Ruoso / Common frog (Rana temporaria) split level view of frog swimming among spawn in pond in breeding season in the Alps, France, June..

Cyril Ruoso / Common frog (Rana temporaria) split level view of frog swimming in pond in breeding season in the Alps, France, June..

Cyril Ruoso / Common frog (Rana temporaria) split level view of frog swimming in pond in breeding season in the Alps, France, June..

Cyril Ruoso / Common frog (Rana temporaria) split level view of frog swimming in pond in breeding season in the Alps, France, June..

Cyril Ruoso / Common frog (Rana temporaria) split level view of frog swimming in pond in breeding season in the Alps, France, June..

Cyril Ruoso / Common frog (Rana temporaria) split level view of frog swimming in pond in breeding season in the Alps, France, June..

Alex Hyde / Alpine Newt (Ichthyosaura / Triturus alpestris) male in mountain pool. Nordtirol, Austrian Alps. July.

Franco Banfi / Swimming pool outside Lotus Bungalow, Candidasa, Bali Island, Indonesia, Pacific Ocean. September 2006.

Nick Upton / Sheba, an adult female Grey seal (Halichoerus grypus), virtually blind since she was rescued as a pup with eye infections and now over 40 years old, swimming in a pool at the Cornish Seal Sanctuary wh...

Nick Upton / Dan Jarvis hand-feeding fish to a recovering Grey seal pup (Halichoerus grypus) 'Uno' in a small swimming pool in the Cornish Seal Sanctuary hospital, Gweek, Cornwall, UK, October. Model released.

Nick Upton / Carer feeding recovering Grey seal pup (Halichoerus grypus) 'Uno' a fish in a small swimming pool, Cornish Seal Sanctuary hospital,, Gweek, Cornwall, UK, October.

Nick Upton / Recovering Grey seal pup (Halichoerus grypus) 'Uno' in a small swimming pool in the Cornish Seal Sanctuary hospital, Gweek, Cornwall, UK, October.

Franco Banfi / Natural ocean pool at Sao Lourenco Bay, Santa Maria Island, Azores, Portugal, Atlantic Ocean.

Onne van der Wal / Accommodation at the Qualia resort on Hamilton Island, Queensland, Australia. November 2012.

Onne van der Wal / Qualia resort Hamilton Island, Whitsundays, Queensland, Australia. November 2012.

Mike Potts / Auckland Island teal (Anas aucklandica) foraging in shallow pool. Flightless bird. Enderby Island, Auckland group (Subantarctic), New Zealand, February.

Christophe Courteau / Capybara (Hydrochoerus hydrochaeris) drinking water from a swimming pool. Hato El Cedral, Llanos, Venezuela.

Vincent Grafhorst / People swimming in pool at the top of falls, Victoria Falls, Zimbabwe

Anup Shah / Long-tailed macaque (Macaca fascicularis) juvenile swimming in a pool of water. Bako National Park, Sarawak, Borneo, Malaysia.

Anup Shah / Long-tailed macaque (Macaca fascicularis) juvenile swimming in a pool of water. Bako National Park, Sarawak, Borneo, Malaysia.

Nick Upton / Two day Common / Eurasian crane chick (Grus grus) swimming in a marshland sedge pool, followed closely by its mother Chris, who was released by the Great Crane Project in 2010, Slimbridge, Gloucesters...

Nick Upton / Two day Common / Eurasian crane chick (Grus grus) swimming in a marshland sedge pool, as its mother Chris, who was released by the Great Crane Project in 2010, preens nearby, Slimbridge, Gloucestershi...

Michel Roggo / North American beaver (Castor canadensis) swimming in the pool around his lodge, Northern Rockies, British Columbia, Canada, July. Taken for the Freshwater Project.

Mike Read / Black-necked grebe (Podiceps nigricollis) juvenile swimming in pool near Tiszaalpar, Hungary, June.

Mike Read / Greylag goose (Anser anser) juveniles swimming in marshland pool near Tiszaalpar, Hungary, June.

Mike Wilkes / Brown rats (Rattus norvegicus) swimming in pool, Warwickshire, England, UK, February

Wild Wonders of Europe / Lundgren / Pool Frog (Pelophylax lessonae) swimming near the surface, near Crisan village, Danube Delta, Romania, June.

Wild Wonders of Europe / Lundgren / Pool Frog (Pelophylax lessonae) split level view, near Crisan village, Danube Delta, Romania, June. Highly commended in the Underwater Category of the GDT Awards Competition 2016.

Wild Wonders of Europe / Lundgren / Pool Frog (Pelophylax lessonae) split level view, near Crisan village, Danube Delta, Romania, June.

Wild Wonders of Europe / Lundgren / Pool Frog (Pelophylax lessonae) viewed from below while swimming, underwater around Crisan village, Danube Delta, Romania, June.

Wild Wonders of Europe / Lundgren / Newly emerged damselfly and resting on the head of a Pool frog (Pelophylax lessonae) Danube Delta, Romania, June.

Wild Wonders of Europe / Lundgren / Pool frog (Pelophylax lessonae) diving and reflected in waters surface at night, Danube Delta, Romania, June.