"Certainly to enter a world of terror, you should not be pushed by someone. You should be called. You should be curious. You should have the heart of an explorer." — Philippe Petit, high-wire artist

Some people might only dream of adventure, but for others, there's no option but to explore the most extreme places on Earth. From the deepest caves to the roughest oceans, from the North Pole to dizzying heights on a high wire — what drives adventurers to constantly push themselves to the brink of human endurance? In this hour, TED speakers share their experiences of going to the edge of our world.

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