With a depth of 35,797 feet at its lowest point, the Challenger Deep, the Mariana trench -- located in the middle of the Pacific Ocean about 14 miles from the Mariana Islands -- is the world's deepest trench. First explored by Jacques Picard and Don Walsh using the HMS Challenger II in the early 1950s, the trench is situated at the site of a convergent plate boundary.
The Tonga Trench is the world's second-deepest oceanic trench. With a maximum depth of 35,702 feet, the Tonga Trench is one of earth's most active fault lines: it is situated at the convergence of the Pacific plate and the Indo-Australian plate. The Pacific island of Tonga experiences a number of hard-hitting earthquakes each year, thanks to the subduction of the Indo-Australian plate; this tectonic action sometimes results in massive tsunamis.
Coming in at number three, the Philippine Trench's deepest point is at 34,580 feet. Sometimes called the Mindanao Deep, this trench was first explored by a group of German scientists in 1927. This trench was formed by the collision of the Continental Sea Plate and the Philippine Sea Plate; the Philippine Sea Plate is being sucked beneath the Continental Sea Plate. This subduction has resulted in the formation of numerous volcanoes.
The Kuril-Kamchatka Trench -- once called the Tuscarora Deep -- goes to a depth of 34,449 feet below sea level. The trench is situated right along the volcanic Kuril Islands chain, which occur off the coast of Japan and Russia. The trench -- about 1,300 kilometers in length -- is believed to have been created during the Cretaceous Period, over 65 million years ago, due to the undersea collision of two tectonic plates.
The Kermadec Trench -- about 32,963 feet deep -- is situated off the coast of New Zealand's Kermadec Islands in the Southwest Pacific Basin. First charted in 1952 by the Danish Galathea expedition, the trench is the creation of the collision of the Pacific plate and the Indo-Australian plate. In total, the trench is about 1,200 kilometers long.
