Yes, underwater volcanoes heat the ocean as well as the land being heated by our molten core.
The link interconnecting the two may be the sun and earth’s magnetic fields.
At iceagenow.com the blogger believes we are at the point in our orbit and precession cycles where our magnetic field is going to reverse polarity, and that shifting is causing the increase in volcanic and seismic activity.
The navigational air control systems of the U.S. are being adjusted now (starting a year or so ago) because a continuing shift in magnetic North has put them out of sync.
And the big question, is this going to destabilize ALL the plates, worldwide?