Shimada Seamount is a seamount in the Pacific Ocean located southwest of Baja California Sur in Mexico. It is a shallow seamount, reaching a depth of 30 metres (98 ft) below sea level^[1] and is a regular single-peaked mountain with a westerly spur and little relief otherwise. A platform lies at a depth of 180 metres (590 ft).^[2] Talus deposits surround the seamount at its base. The seafloor underneath Shimada is between 18 million and 21 million years old and lies at a depth of about 4,100 metres (13,500 ft); other than abyssal hills at a distance of up to 1 kilometre (0.62 mi) from Shimada, Shimada is isolated.^[2] Volcanic rocks taken from Shimada are considered to be icelandites.^[3]

Most seamounts form at mid-ocean ridges, but hotspots and transform faults can also produce seamounts.^[1] These mechanisms cannot really explain the origin of Shimada Seamount, however;^[2] it may be part of a hotspot trace.^[4] Evidence from core samples around the seamount, the appearance of the summit area,^[5] and the presence of thin manganese crusts imply an age of about 10,000 years for some volcanic rocks at Shimada; the rocks are too young to be dated by potassium-argon dating, and all the evidence indicates that volcanic activity at Shimada is of late Quaternary-Holocene age.^[6]

Possibly alive Lithothamnium corals have been dredged at Shimada from a depth of 110 to 130 metres (360 to 430 ft).^[7]

Shimada Seamount is named for the American fisheries scientist Bell M. Shimada (1922–1958).^[8] It has been known under a variety of names throughout its history, including Shimada Bank, Shamada Seamount, Hurricane Bank and Allaire Bank.^[9]