Danny Green / Waxwings (Bombycilla garrulus) feeding on berries in snow. Finland, March

Marion Vollborn/ BIA / Leopard (Panthera pardus) cub, Okavango Delta, Botswana

Andres M. Dominguez/ BIA / Common Tern (Sterna hirundo) flying with fish prey, Danube Delta, Romania

Marion Vollborn/ BIA / African Lion (Panthera leo) cubs drinking at waterhole, Okavango Delta, Botswana

Michel Roggo / Aquatic plants on the river bed of the Okavango river, Okavango Delta, Botswana, June 2014 . Photographed for The Freshwater Project

Michel Roggo / View of African fish eagle (Haliaeetus vocifer),from underwater, trying to catch a fish on the surface, Okavango Delta, Botswana, June. Photographed for The Freshwater Project

Orsolya Haarberg / View of the Laitaure delta and Rapa River, Sarek National Park, Laponia World Heritage Site, Sweden, September 2013.

Juan Carlos Munoz / Aerial view of Delta Sierpe River Terraba, Corcovado National Park, Osa Peninsula, Puntarenas Province, Costa Rica. December 2014.

Juan Carlos Munoz / Aerial view of Delta Sierpe River Terraba, Corcovado National Park, Osa Peninsula, Puntarenas Province, Costa Rica. December 2014.

Staffan Widstrand / Aquatic warbler (Acrocephalus paludicola) Nemunas River Delta, Lithuania. May. Vulnerable species species.

Sven Zacek / Autumn trees on the Rapa River Delta, aerial view, Rapadalen Sarek National Park, Sweden, September 2009.

Pal Hermansen / Aerial view of river delta and coast, South West Iceland, June 2014.

Pal Hermansen / Aerial view of river delta, South West Iceland, June 2014. Finalist in the Art of Nature Category of the Big Picture Competition 2015.

Pal Hermansen / Aerial view of river delta, South West Iceland, June 2014.

Pal Hermansen / Aerial view of river delta, South West Iceland, June 2014.

Hiroya Minakuchi / Wattled Crane (Bugeranus carunculatus) flock flying, Okavango Delta, Botswana

Hiroya Minakuchi / Hippopotamus (Hippopotamus amphibius) calves, Okavango Delta, Botswana

Sean Crane / Lechwe (Kobus leche) running through water, Okavango Delta, Botswana

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

Laurent Geslin / Female African lion (Panthera leo) swimming across the Khwai river, Okavango Delta, Moremi reserve, Botswana, sequence 5/5

Laurent Geslin / Female African lion (Panthera leo) jumping in to the Khwai river, Okavango Delta, Moremi reserve, Botswana, sequence 4/5

Laurent Geslin / Female African lion (Panthera leo) jumping in to the Khwai river, Okavango Delta, Moremi reserve, Botswana, sequence 2/5

Laurent Geslin / Female African lion (Panthera leo) jumping in to the Khwai river, Okavango Delta, Moremi reserve, Botswana, sequence 1/5

Erlend Haarberg,Erlend Haarberg / Aerial view down river to the east of the Hofsjakull glacier and west of the Sprengisandur upland desert. Innumerable rivulets flow from beneath the glacier in this area of tundra which abounds in pon...

Christophe Courteau / Red lechwe pair running & jumping in swamp {Kobus leche}. Khwai river, Moremi GR, Botswana

Cheryl-Samantha Owen / Tribal elder and chief of his village, Orma village, pastoralist tribe living in Tana River delta, Kenya, East Africa 2010. No release available.

Cheryl-Samantha Owen / A young Orma man herds cattle, Tana River Delta, Kenya, East Africa 2011. No release available.

Jack Dykinga / Colorado River Delta, with watercourse sculpted patterns eroded into the salt / silt flats near the Sea of Cortez, La Reserva del Golfo, Baja, Mexico

Erlend Haarberg / Aerial view of river delta and Landeyjarsandur beach, South coast of Iceland, September 2010

Pete Oxford / African Lion (Panthera leo) male portrait, Moremi Game Reserve, Okavango Delta, Botswana

Orsolya Haarberg / Aerial view of Laitaure Delta and Rapa river, Lappland, Sweden, September 2006.

Gerrit Vyn / Aerial view of oiled bird nesting colonies in Barataria Bay area of the Mississippi River delta, with oil spill containment booms attempting to prevent more oil coming ashore. These waters are contami...

David Woodfall / Villagers living in former river bed now dry due to siltation, complex effects of climate change, Ganges delta, Bangladesh, November 2008

David Woodfall / Dark monsoon rain clouds over the Pasur river, Ganges delta, Bangladesh, November 2008

Wild Wonders of Europe / della Ferrera / Cultivated part of the lower Neretva river delta, Dalmatia region, Croatia, May 2009

Wild Wonders of Europe / della Ferrera / Cultivated part of the lower Neretva river delta with a sinkhole in marshland surrounded by Reeds (Phragmites sp) Dalmatia region, Croatia, May 2009

Wild Wonders of Europe / della Ferrera / Sinkhole in marshland covered in Reeds (Phragmites sp) near the lower Neretva river delta, Dalmatia region, Croatia, May 2009

Wild Wonders of Europe / della Ferrera / House martin (Delichon urbicum) and a Swallow (Hirundo rustica) collecting mud to build nests, Neretva river delta, Dalmatia region, Croatia, May 2009

Wild Wonders of Europe / della Ferrera / Neretva river delta at sunset, eastern coast of the Adriatic sea, Dalmatia region, Croatia, May 2009

Wild Wonders of Europe / della Ferrera / Neretva river delta, with Harestail grass (Lagurus ovatus) in the foreground, Mediterranean cypresses (Cupressus sempervirens) on the far bank, Galicak area, Dalmatia region, Croatia, May 2009

Wild Wonders of Europe / Geidemark / River delta at dawn, Karavasta Lagoons National Park, Albania, June 2009

Wild Wonders of Europe / Carwardine / Aerial view of the Skjalfandafljot river delta, Northern Iceland, July 2009

Wild Wonders of Europe / Carwardine / Aerial view of the Skjalfandafljot river delta, Northern Iceland, June 2009

Wild Wonders of Europe / Presti / River Danube with reflections in water, Danube Delta Scenery, Romania, May 2009

Wild Wonders of Europe / Presti / Trees on the river bank reflected in water, Danube Delta Scenery, Romania, May 2009

Wild Wonders of Europe / Presti / Eastern white pelican (Pelecanus onolocratus) taking off from river, Danube Delta, Romania, May 2009

Suzi Eszterhas / African Wild Dog (Lycaon pictus) six to eight week old pup running, Okavango Delta, Botswana

Suzi Eszterhas / African Wild Dog (Lycaon pictus), Okavango Delta, Botswana

Suzi Eszterhas / African Wild Dog (Lycaon pictus) six to eight week old pup, Okavango Delta, Botswana

Vincent Grafhorst / Black-faced Vervet Monkey (Cercopithecus aethiops) baby clinging to mother, Moremi Game Reserve, Okavango Delta, Botswana

Vincent Grafhorst / African Lion (Panthera leo) pair copulating, Moremi Game Reserve, Okavango Delta, Botswana

Vincent Grafhorst / African Lion (Panthera leo) male roaring, Moremi Game Reserve, Okavango Delta, Botswana

Vincent Grafhorst / African Lion (Panthera leo) pair copulating, Moremi Game Reserve, Okavango Delta, Botswana

Fabio Liverani / Five European Flamingos (Phoenicopterus ruber roseus) in flight against evening sky, delta region of the River Po, Italy

Theo Allofs / Lechwe (Kobus leche) and Cattle Egret (Bubulcus ibis) in Moremi Game Reserve, Okavango Delta, Botswana

Richard Du Toit / Southern Giraffe (Giraffa giraffa) four running across wetland, Okavango Delta, Botswana

Richard Du Toit / African Lion (Panthera leo) females hunting Cape Buffalo (Syncerus caffer) herd, Okavango Delta, Botswana

Richard Du Toit / African Lion (Panthera leo) male pair, Okavango Delta, Botswana

Richard Du Toit / Cape Buffalo (Syncerus caffer) herd, Okavango Delta, Botswana

Staffan Widstrand / Aerial view of tundra wetland, Kolyma River Delta, Siberia

Gerry Ellis / African Elephant (Loxodonta africana) herd of adults and calves running, Linyanti Swamp, Botswana

Gerry Ellis / Sunset and storm clouds over waterhole, Kwando River flood plain, Linyanti Swamp, Okavango Delta, Botswana

Gerry Ellis / African Lion (Panthera leo) mother with cub, Moremi Wildlife Reserve, Okavango Delta, Botswana

Konrad Wothe / Flight safari, Okavango Delta, Botswana

Konrad Wothe / Safari airplane flying over the flooded Okavango Delta, Botswana

Pete Oxford / Hippopotamus (Hippopotamus amphibius) in river at dusk. Okavango Delta, Botswana, Southern-Africa

Gerry Ellis / Rainforest logging activities near eastern boundary of the Kikori Delta, Papua New Guinea

Gerry Ellis / Logging road and erosion in lowland tropical rainforest east of Aird River Delta, Kikori Basin, Papua New Guinea

Gerry Ellis / Aerial view of gulf coast region showing lowland tropical rainforest and winding rivers, Kikori Delta, Papua New Guinea

Michael Quinton / Trumpeter Swan (Cygnus buccinator) pair on lake, Copper River Delta, Alaska

Pete Oxford / African elephant feeding on papyrus in river, Okavango Delta, Botswana

Espen Bergersen / Snow covered river delta. Iceland, October 2017

Espen Bergersen / Northern lights (Aurora Borealis) over river delta, Southern Iceland. October 2017

Espen Bergersen / Aerial view of Stakihnukur mountain and river delta. Soutnern Iceland

Espen Bergersen / Aerial view of river in Landmannalaugar. Iceland. October 2017

Staffan Widstrand / Great white heron / egret (Ardea / Egretta alba) taking off, Nemunas Delta Nature Reserve, Lithuania.

Jack Dykinga / Patterns in the tidal flats of the delta where the delta is swept by tidal encroachment from the Gulf of California. Evidence of the fresh water flow is observable as plant life turns green. Colorado...

Jack Dykinga / Patterns in the tidal flats of the delta where the delta is swept by tidal encroachment from the Gulf of California. Evidence of the fresh water flow is observable as plant life turns green. Colorado...

Jack Dykinga / Patterns in the tidal flats of the delta where the delta is swept by tidal encroachment from the Gulf of California. Evidence of the fresh water flow is observable as plant life turns green. Colorado...

Jack Dykinga / Cienega de Santa Clara / Santa Clara wetlands which are supported by agricultural waste water from the U.S. and Mexico. Colorado River Delta region's estuary marshes. USA September 2019.. Aerial s...

Jack Dykinga / Cienega de Santa Clara / Santa Clara wetlands which are supported by agricultural waste water from the U.S. and Mexico. Colorado River Delta region's estuary marshes. USA September 2019. Aerial su...

Jack Dykinga / Cienega de Santa Clara / Santa Clara wetlands which are supported by agricultural waste water from the U.S. and Mexico. Colorado River Delta region's estuary marshes. USA September 2019.. Aerial s...

Jack Dykinga / Patterns in the tidal flats of the Colorado River Delta where the delta is swept by tidal encroachment from the Gulf of California. Colorado River Delta, Baja California, Mexico. September 2019. A...

Jack Dykinga / Patterns in the tidal flats of the delta where the delta is swept by tidal encroachment from the Gulf of California. Evidence of the fresh water flow is observable as plant life turns green. Colorado...

Jack Dykinga / Patterns in the tidal flats of the delta where the delta is swept by tidal encroachment from the Gulf of California. Evidence of the fresh water flow is observable as plant life turns green. Colorado...

Jack Dykinga / Cienega de Santa Clara / Santa Clara wetlands which are supported by agricultural waste water from the U.S. and Mexico. Colorado River Delta region's estuary marshes. USA September 2019. Aerial su...

Jack Dykinga / Patterns in the tidal flats of the Colorado River Delta where the delta is swept by tidal encroachment from the Gulf of California. Receding tide causes waterfalls approximately eight feet high, as wa...

Jack Dykinga / Patterns in the tidal flats of the Colorado River Delta where the delta is swept by tidal encroachment from the Gulf of California. Receding tide causes waterfalls approximately eight feet high, as wa...

Jack Dykinga / Patterns in the tidal flats of the Colorado River Delta where the delta is swept by tidal encroachment from the Gulf of California. Receding tide causes waterfalls approximately eight feet high, as wa...

Jack Dykinga / Patterns in the tidal flats of the Colorado River Delta where the delta is swept by tidal encroachment from the Gulf of California. Receding tide causes waterfalls approximately eight feet high, as...

Jack Dykinga / Patterns in the tidal flats of the Colorado River Delta where the delta is swept by tidal encroachment from the Gulf of California. Receding tide causes waterfalls approximately eight feet high, as wa...

Jack Dykinga / Patterns in the tidal flats of the Colorado River Delta where the delta is swept by tidal encroachment from the Gulf of California. Receding tide causes waterfalls approximately eight feet high, as...

Staffan Widstrand / Black tern (Chlidonias nigra) feeding chick on floating vegetation. Nemunas Delta Nature Reserve, Lithuania. July.

Juan Carlos Munoz / Santona, Victoria and Joyel Marshes Natural Park. Aerial view of estuary out to the Cantabrian Sea. Cantabria, Spain. March 2019.

Juan Carlos Munoz / Santona, Victoria and Joyel Marshes Natural Park. Aerial view of estuary. Cantabria, Spain. March 2019.

Juan Carlos Munoz / Santona, Victoria and Joyel Marshes Natural Park. Aerial view of estuary. Cantabria, Spain. March 2019.

Juan Carlos Munoz / Mist on a shallow channel, Danube Delta UNESCO World Heritage Site, Tulcea County, Romania, October.