I can’t imagine living under water would be much fun either, I imagine the bottom of the ocean in high grav would be absolutely unlivable due to the pressure
Also, I’m not entirely sure how it works but divers have to come out of the water really slowly and carefully so they don’t get the bends, imagine that where the water pressure keeps changing
Infact imagine any underwater structure where the pressure continuously changes dramatically
Also also the tides would be going absolutely crazy overhead
All that said that would make it even cooler to have some kind of hermit character, maybe a powerful wizard living under the sea despite all the hazards and difficulties