“The undersea Marsili, 9,800 feet tall and located some 90 miles southwest of Naples, has not erupted since the start of recorded history. It is 44 miles long and 19 miles wide, and its crater is about a quarter mile below the surface of the Tyrrhenian Sea.”
http://www.foxnews.com/scitech/2010/03/29/undersea-volcano-threatens-italy/?test=latestnews
