Colin Monteath/ Hedgehog House / Purakaunui Falls, Catlins, New Zealand

Jeff Foott / Indian Rhubarb (Darmera peltata) growing on rock in river, Cascade Creek, Yosemite National Park, California

Jeff Foott / Spring run-off, Cascade Creek, Yosemite National Park, California

Guy Edwardes / View of hikers from behind the Pericnik Waterfall, Slovenia, October 2018.

Staffan Widstrand / Wild Wonders of China / Tree frog (Amolops afghanus) female sitting on moss Tongbiguan Nature Reserve, Dehong prefecture, Yunnan province, China, May.

Yva Momatiuk & John Eastcott / Tourist next to cascades, Dynjandi Waterfall, Westfjords, Iceland

Greg Basco/ BIA / Nauyaca Waterfalls, Dominical, Costa Rica

Tony Wu / Humpback whale (Megaptera novaeangliae) executing a dramatic tail slap, throwing up a cascade of water with its powerful fluke, Vava'u, Tonga, South Pacific

Orsolya Haarberg / View of a rainbow in the spray of Bjornefossen Waterfall, Saltfjellet-Svartisen National Park, Norway, August 2015.

Jeff Vanuga / Night stars over Yosemite Falls, Yosemite National Park, California, USA, May 2014.

Juan Carlos Munoz / Water cascading down Toberia falls, Andoin, Sierra Entzia Natural Park, Alava, Basque Country, Spain, April.

Bruno D'Amicis / Tisisat Falls / Blue Nile Falls along the Blue Nile, south of Bahir Dar, Lake Tana Biosphere Reserve, Ethiopia. December 2013.