Kuril Trench, deep submarine depression in the western Pacific Ocean, situated on the east side of the Kamchatka Peninsula, the Kuril Islands, and Hokkaido island, Japan. Extending for about 1,800 miles (2,900 km) north-south, it has a maximum depth of 34,587 feet (10,542 metres) and covers a total area of 102,000 square miles (264,000 square km). The steep slopes of the trench are characterized in places by an intermediate bench, or series of steps or terraces, which are sometimes interpreted as the scarps of giant, gravitationally slumped sheets of rock. The Kuril Trench marks the beginning of a chain of oceanic trenches extending from the southwestern edge of the Bering Sea to the southern tip of the Philippine Trench. Such trenches mark the convergence and collision of the Pacific Plate with plates to the west.