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.