The Trench sits like a crescent-shaped dent in the floor of the Pacific Ocean, extending over 1500 miles long with an average width of around 43 miles and a depth of almost 7 miles (or just under 36,201 feet). It's deeper than Mount Everest (29,037 ft); at that depth, the weight of water above makes the pressure in the Trench around 1000 times higher than it would be on the ground. Floor vents release bubbles of liquid sulfur and carbon dioxide ...