Jennifer Jordan and dog Jack cross country ski the Berma Road near Potomac, Maryland, United States of America, North America

Jennifer Jordan and dog Jack cross country ski the Berma Road near Potomac, Maryland, United States of America, North America

Jennifer Jordan and dog Jack cross country ski the Berma Road near Potomac, Maryland, United States of America, North America

Tourists hiking by frozen lake in the Arctic Circle on Ringvassoya Island in the region of Tromso, Northern Norway

Cross-country skier near Hinterzarten, Black Forest, Baden-Wuerttemberg, Germany

Cross country skiers, Close-up of shoes and binding, Flims, Grisons, Switzerland

Cross-country skier near Hinterzarten, Black Forest, Baden-Wuerttemberg, Germany

Cross-country skier near Hinterzarten, Black Forest, Baden-Wuerttemberg, Germany

Cross-country skier near Hinterzarten, Black Forest, Baden-Wuerttemberg, Germany

Elephants (Loxodonta africana), bull and young crossing the road in front of tourists on a game drive, Etosha National Park, Namibia, Africa

Tiger (Panthera tigris), walking in front of tourist vehicles on a safari, Ranthambore National Park, Rajasthan, India, Asia

Tiger (Panthera tigris), walking in front of tourist vehicles on a safari, Ranthambore National Park, Rajasthan, India, Asia

Tiger (Panthera tigris), walking in front of tourist vehicles on a safari, Ranthambore National Park, Rajasthan, India, Asia

Group of lions (Panthera leo) walking past a safari vehicle, Hlane Royal National Park, Swaziland, Africa

Zebras in front of a jeep with safari tourists, Ngorongoro Crater, Tanzania, Africa