Young child with its mother in Burkina Faso, formerly Upper Volta, Africa.

Men swimming in the icy glacial lakes of Mount Cook National Park; Canterbury, New Zealand

Men swimming in the icy glacial lakes of Mount Cook National Park; Canterbury, New Zealand

Two blue wildebeest (Connochaetes taurinus) go down a steep, dirt riverbank gulley while others stand watching on the edge, Serengeti National Park, Tanzania, Africa

Viewpoint, looking down at feet standing next to foamy surf on Kamaole Beach at the water's edge, Kihei, Maui, Hawaii, United States of America

Girls in a row at edge of swimming pool

Girl standing at edge of swimming pool with inflatable ring