Large four peaked series of seamounts in open sea. (aggressor.com)
Examples of extinct volcanoes are many volcanoes on the Hawaiian — Emperor seamount chain in the Pacific Ocean (although some volcanoes at the eastern end of the chain are active), Hohentwiel in Germany, Shiprock in New Mexico, and Zuidwal volcano in the Netherlands. (en.wikipedia.org)
«Undersea volcano: Axial Seamount off Northwest coast is erupting.» (sciencedaily.com)