But human beings are also notoriously bad at doing what's best for us. And so we push ourselves to places we were never meant to survive in, from the bottom of the ocean to the top of the world.
In honor of Earth Day 2011, we take a look at some of the most extreme places on the planet.
At 29,193 feet above sea level, Mount Everest has attracted adventure seekers wanting to stand at the vault of the heavens ever since Sir Edmund Hillary and Tenzing Norgay made the first ascent in 1953.
At the top of Mount Everest there is only about a third of the oxygen available at sea level. Most climbers use supplemental oxygen to reach the top, but the truly hardened adventurer does it au naturel.