The Mariana Trench is the deepest point on Earth, located in the western Pacific Ocean west of the Mariana Islands. It is over 7 miles deep at its lowest point. The trench formed as the dense Philippine Plate subducts under the lighter Eurasian Plate, dragging the edge of the continental crust downward. While proposed as a nuclear waste disposal site, dumping nuclear waste is prohibited and the large earthquakes of subduction zones make it unpredictable and potentially unsafe. The trench is also used as a passage by submarines circling the Pacific Ocean.