There are some banks that were reported in the 19th century by navigators, such as Wachusett Reef, whose existence is doubtful.In tropical areas some banks are submerged atolls.[1] Seamounts, by contrast, are mountains rising from the deep sea and are steeper and higher in comparison to the surrounding seabed.[2] Examples of these are Pioneer and Guide Seamounts, west of the Farallon Islands.The Pioneer Seamount has a depth of 1,000 meters,[2] In other cases, parts of a bank may reach above the water surface, thereby forming islands.