Local guide sitting in one the Laas Geel caves, Somaliland, Somalia, Africa

Sign for interpretation centre, Cueva del Llano, La Oliva, Fuerteventura, Canary Islands, Spain, Atlantic, Europe

Guide pointing at cave paintings in Lass Geel caves, Somaliland, Somalia, Africa

Inside ice cave under the Vatnajokull Glacier, with cave guide looking up to hole in cave roof, near Jokulsarlon, South Iceland, Polar Regions

Cave guide wearing protective hard hat inside one of the ice caves under the Vatnajokull Glacier, South Iceland, Polar Regions

Cueva de Los Verdes, volcaninc cave, Lanzarote, Canary Islands, Spain, Europe

A Filipino Tour Guide Holds A Lantern Inside Sumaging Cave Or Big Cave Near Sagada, Luzon, Philippines

A Filipino Tour Guide Holds A Lantern Inside Sumaging Cave Or Big Cave Near Sagada, Luzon, Philippines

A Filipino Tour Guide Holds A Lantern Inside Sumaging Cave Or Big Cave Near Sagada, Luzon Philippines