And today's CNN 10 take us in depth because you really can't go anywhere more in depth than the Challenger Deep, the deepest point of the world's deepest trench in the world's deepest ocean. We're talking about the Mariana Trench in the Pacific Ocean. National Geographic describes it as a scar in the Earth's crust. It's located about seven miles beneath the waves. The trench measures more than 1,500 miles long and it's 43 miles wide on average. So we're talking about a pretty big scar overall and the Challenger Deep is near the southern end of it. It takes a feat of engineering just to get there. It takes hours of diving to hit bottom and it's largely an unexplored frontier.
Even though thousands of people have reached the top of the world on Mt. Everest, fewer than 25 have reached the bottom of it in the Challenger Deep. New Zealander Rob McCallum is one of them. On April 8th, he became the first person from his country to go there and he went along with Tim Macdonald, the first person from Australia to complete the feat.