Every now and again the world takes notice of someone who has done something truly extraordinary. Whether that involves jumping from a balloon on the edge of the earth's atmosphere, trekking through the depths of the Antarctic winter or sailing solo around the world, these exceptional feats of endurance and bravery capture the imaginations of individuals around the globe. The World's Most Extreme Challenges explores how hard and far individuals are willing to push themselves in their pursuit of the ultimate physical challenge. Some of the challenges featured are professional races, but most are simply acts of supreme physical endurance that few people can imagine, let alone conceive attempting. Providing an in-depth look at these events, profiling both the challenges and the individuals who take part in them, this is a celebration of what human beings can do when they decide to push themselves to their limits - and beyond. Showcasing 50 of the hardest physical tests, including: Cycling around the world Jumping from outer space Running around Australia Surfing the world's biggest wave Swimming the Atlantic Ocean Trekking to the North Pole Holding your breath for 22 minutes Trekking across the Sahara Climbing the world's highest mountains The Triple Deca Ironman