The Mariana Trench, located in the western Pacific Ocean, is the deepest oceanic trench on Earth. Measuring about 1,580 miles in length and 43 miles in width, its maximum known depth is 36,037 feet (about 7 miles), located at the southern end of a small valley in its floor known as the Challenger Deep. If Mount Everest were placed into the trench at this point, its peak would still be underwater by more than a mile. The first descent was performed by U.S. Navy Lt. Don Walsh and Swiss oceanographer and engineer Jacques Piccard aboard the bathyscaph Trieste. The vessel was designed by Piccard and his father Auguste and sold to the U. S. Navy for this expedition. Here is Part 1 of the story, told by Lt. Walsh himself, and transcribed by me in Anniversary Gregg for the blog.