Deep-sea Trenches

one of the most characteristic elements of the relief of the transitional zone between a continent and the ocean, consisting in a long, narrow lowering in the ocean floor to a depth of over 6,000 m. Deep-sea trenches are usually located on the outer (ocean) side of the mountain ranges of the island arcs. Geologically they represent contemporary geosynclinal structures. The deepest trenches, such as the Marianas Trench, reaching a depth of 11,022 m, are found in the Pacific Ocean.