A warning sign at the start of the Hermit Canyon Trail stating that getting to the bottom is optional, but getting back to the top is mandatory, Grand Canyon, Arizona, United States of America, North America

The Twelfth Station of the Cross on the trail to the top of this tourist park with its world peace tower and worship houses of five major religions, Bukit Kasih, Minahasa, North Sulawesi, Indonesia, Southeast Asia, Asia

Woman walking on an exposed trail at a rockface, Brunnstein, Bavarian Prealps, Upper Bavaria, Bavaria, Germany

Walkers on 5-day Overland Track, Overland Track, Cradle Mountain-Lake St Clair National Park, Tasmania, Australia

Treetops Adventure walkway at the Capilano Suspension Bridge, tourist attraction, Vancouver, British Columbia, Canada, North America

Tree-top walk, Neuschoenau, Bavarian Forest National Park, Lower Bavaria, Bavaria, Germany, Europe

Peeled bark, in the back the peeled spruce logs (Piceoideae) Neunhof, Middle Franconia, Bavaria, Germany, Europe

Peeled bark, in the back the peeled spruce logs (Piceoideae) Neunhof, Middle Franconia, Bavaria, Germany, Europe

Longest treetop path of the world, Kopfing, Upper Austria, Europe

From the left the Algunder Waal (canal) hiking trail the Dorf Tirol below castle de Fontana and the mountain Ilfinger peak, near Meran, South Tyrol, Italy

Adventure trail Waldwipfelweg in the snow-covered winter landscape in the Bavarian Forest near St. Englmar, Bavaria, Germany, Europe

Adventure trail Waldwipfelweg in the snow-covered winter landscape in the Bavarian Forest near St. Englmar, Bavaria, Germany, Europe

Observation tower at the tree top path Salzkammergut am Gruenberg, Gmunden, Salzkammergut, Upper Austria, Austria, Europe

Tree-top walk, Neuschoenau, Bavarian Forest National Park, Lower Bavaria, Bavaria, Germany, Europe

Treetop path in the forest, Fuessen, Allgaeu, Bavaria, Germany, Europe

Tree-top walk, Neuschoenau, Bavarian Forest National Park, Lower Bavaria, Bavaria, Germany, Europe

Observation tower at the tree top path Salzkammergut am Gruenberg, Gmunden, Salzkammergut, Upper Austria, Austria, Europe

Tree-top walk, Neuschoenau, Bavarian Forest National Park, Lower Bavaria, Bavaria, Germany, Europe

Aerial view, cemetery, park, Haspe, Hagen, Ruhrgebiet region, North Rhine-Westphalia, Germany, Europe

World's longest tree top walk, view from the 44 metre high tree platform, Neuschoenau, Bavarian Forest National Park, Bavaria, Germany, Europe

Cable cars, Hochfelln, Chiemgau Alps, Upper Bavaria, Germany, Europe

Noering Church, Innernoering, Nockberge mountains, Carinthia, Austria, Europe

Woman hiking along the Dempster Highway enjoying the scenery on top of Sapper Hill; Yukon, Canada

View taken from behind of two women sitting on a mountain top with their dog enjoying the view, while exploring and photographing the amazing scenery of the Yukon along the Sam McGee Trail near Carcross, Yukon, Carcross, Yukon Territory, Canada

Snowboarding on a run at Sun Peaks ski resort with snow ghosts at the top of the mountain, Kamloops, British Columbia, Canada