The world's deepest dive 11km down

Don Walsh was the first to go to the very bottom of the deepest part of the ocean in 1960 in a specially designed submarine, the Bathyscaphe Trieste. The water pressure was 800 tonnes per square inch, and the successful mission to "Challenger Deep" in the Mariana Trench under the western Pacific, was a technological breakthrough in marine engineering. Don Walsh describes the dive to Rebecca Kesby, and explains why understanding the deep ocean is crucial in the fight to reduce climate change. (Photo: The Bathyscaphe Trieste in 1960. Getty Images)

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Eye-witness accounts brought to life by archive. Witness History is for those fascinated by the past. We take you to the events that have shaped our world through the eyes of the people who were there. For nine minutes every day, we take you back in time and all over the world, to examine wars, coups, scientific discoveries, cultural moments and much more. Recent episodes explore everything from the death of Adolf Hitler, the first spacewalk and the making of the movie Jaws, to celebrity tortoise Lonesome George, the Kobe earthquake and the invention of superglue. We look at the lives of some of the most famous leaders, artists, scientists and personalities in history, including: Eva Peron – Argentina’s Evita; President Ronald Reagan and his famous ‘tear down this wall’ speech; Thomas Keneally on why he wrote Schindler’s List; and Jacques Derrida, France’s ‘rock star’ philosopher. You can learn all about fascinating and surprising stories, such as the civil rights swimming protest, the disastrous D-Day rehearsal, and the death of one of the world’s oldest languages.