Pacific sea floor. Hemispherical artwork of the topography of the sea floor of the Pacific Ocean, showing underwater mountains, continental shelves, mid-ocean ridges and subduction zones associated with the Pacific Plate, one of the Earth's tectonic plates. Some of the volcanic peaks emerge above the waters to form islands such as Hawaii. The mid-ocean ridge at lower right is the East Pacific Rise. Part of the Australian Plate is at lower left. The Aleutian Trench is across top. These Pacific Plate boundaries give rise to the 'Ring of Fire', a series of earthquake-prone regions and volcanoes surrounding the Pacific.