> Not to mention all the sea life that isn’t going to respond well to high temp water spewing out..
Ideally, you're not dumping the hot water back into the harbor. At least from a naive theory perspective, you could put huge cooling towers on deck and cool the reactor 100% through evaporative cooling. Bonus: the huge steam/mist cloud out of the cooling tower could help delay global warming through marine cloud brightening [0]. Whether the deck of a floating reactor has enough space and stability to support cooling towers of the appropriate size is a question for the engineers.
That's how most reactors in first world countries with temperate climates work anyway. Because it really messes up the biosphere of your river/coast, if you just dump 3GWh of thermal power straight into the water.