Visit extreme locales, including Mount Everest's Khumbu Icefall and the dangers it presents to Sherpas; the Grand Canyon, where conservationists try to ensure a condor chick's survival; and the slopes of Mount Kilimanjaro, there farmers battle with elephants.

See wonders created by the grand and unpredictable power of water, including Victoria Falls, where men risk death to reach fishing pools; the Camargue, where it's man versus bull; and ocean reefs, where a guardian seeks a manta ray to help save the species.

In many of the world's most extraordinary natural wonders, wildlife holds the key to survival for the people who live there. But even there, animals can be foes, as well as friends.

In some natural wonders, people must push themselves to the absolute limit in order to survive. For the people who call these extraordinary places home, survival requires great skill, determination, and courage.