There are plenty of hot energy spots on the ocean floor. Imagine all this water just waiting to be boiled at high pressure geothermal area spots and the steam used to drive thermal turbines.
The idea could be extended by placing a large water pipe from the sea surface down to the thermal plant and use the falling water to drive conventional hydro turbines for electricity production. The same water would than be used through a closed loop system by underwater geothermal power plant thermal turbine for electricity production.
This is a closed loop system both from technical and natural point of view.
Call this a natural double dip power plant.