A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface (sea level), and thus is not an island. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to 1,000–4,000 metres (3,300–13,100 ft) in height. They are defined by oceanographers as independent features that rise to at least 1,000 metres (3,281 ft) above the seafloor, characteristically of conical form.