Britannia Guyots

The Britannia Guyots are a line of extinct volcanic seamounts in the Tasmantid Seamount Chain.
They are basaltic volcanoes that erupted between 17,600,000 and 20,800,000 years ago, with survey data that indicates they rise about above the local sea floor to a minimum depth of. The sediments deposited on top of the alkali olivine basalt originate from the early Middle Miocene when the ocean water was tropical to subtropical. They were described as seamounts in 1961.
The waters above it are incorporated in the Central Eastern Marine Park, an Australian marine park.