To be clear, that acronym is for "Small Modular Reactors". Just in case anyone else was confused or thought it was a NATO/OTAN thing.
But they're still not cost effective which is why the biggest question with nuclear plants always is 'how much subsidy can we get'.
In deeper waters a tsunami isn't very noticeable and we already have proven power cable technology from wind power far out at sea.
Reactors on various vessels have entirely different working parameters from those on shore and there the consumer is right next to the reactor. But in the case that you sketch you'd have a floating reactor tied to a stationary power grid that somehow is resilient to the worst that the ocean can throw at it. I just can't see that working, even in the short term, let alone over the service life of a typical nuclear reactor.
Ship-borne nuclear reactors have been used for emergency power, but that's not a structural solution and it is also a very expensive one (compared to land based generation that power is quite expensive). So as soon as possible the emergency use is discontinued and it's back to land based solutions.
Off-shore windpower shows the complexity of ocean based power generation quite well and they have a much simpler safety situation, maintenance schedule, degree of complexity and so on. And even there the challenges are far more serious than the land based equivalent.
Some work has been done on floating wind farms:
https://en.wikipedia.org/wiki/Floating_wind_turbine
But the economics are not comparable to those of anchored turbines (either off-shore on on-shore). Likely something similar would hold for nuclear power, that off-shore nuclear power would by default be far more expensive than on-shore nuclear power and that is already economically not feasible without massive subsidies.