Weird and scary creatures found at the deepest part of the ocean, the Mariana Trench. The Mariana Trench is located in the Pacific Ocean, just east of the 14 Mariana Islands near Japan. It is 11,033 meters (36,201 feet), (6033.5) fathoms deep. The Pressure at the deepest part of the Mariana Trench is over 8 tons per square inch. The Mariana Trench is 2, 542 km (1,580 miles) long and 69 km (43 miles) wide.