Large submarine volcanic mountain rising at least 3,000 ft (1,000 m) above the surrounding seafloor; smaller submarine volcanoes are called sea knolls, and flat-topped seamounts are called guyots.
Seamounts are abundant and occur in all major ocean basins. By the late 1970s more than 10,000 seamounts had been reported in the Pacific Ocean basin alone. Virtually every oceanographic expedition discovers new seamounts, and it is estimated that about 20,000 exist worldwide.