High Quality Content by WIKIPEDIA articles! A bank is a shoal a comparatively shallow area or an underwater hill on the continental shelf surrounded by deeper water. It may be of volcanic nature. Banks may be carbonate or terrigenous. As they are not associated with any landmass, banks have no outside source of sediments. Carbonate banks are typically platforms, rising from the ocean depths, whereas terrigenous banks are elevated sedimentary deposits. Seamounts, by contrast, are mountains, of volcanic origin, rising from the deep sea, and are steeper, and higher in comparison to the surrounding seabed. Examples are Pioneer and Guide Seamounts, west of the Farallon Islands. The Pioneer Seamount has a depth of 1,000 meters, In other cases, parts of a bank may reach above the water surface, thereby forming islands.