I understand that a larger ocean planet (or waterworld) will have an ocean less deep that a smaller one since pressures get higher faster as you go deeper (transition to ice VII). Assuming my planet has active volcanism due to residual heat and radioactive material in the core, I would hope that rocky material could "break through" the ice VII and produce underwater mountains. I also would like to add contributing material from asteroid/comet bombardment from space.
Could there be a plausible scenario for life starting in such a situation or would the water/rock interface be under such high pressure that this would be unlikely?
What about panspermia life from a "doomed" planet in the same system that could build floating islands of biomass? And what about the crazy winds and waves. Would they come to an equilibrium and be tolerable for lifeforms??