Not building seabases (cuz its just wrong to be building on these guys) , but like gardens(creepvine bloodkelp acidshroom etc) and a beacon that follows it
What about acid rain, that will only occur after you make a room that will damage you if you or your base is about above 30 metres B-S-L it/you will take severe damage
The water will stay acidic for 2 days then everything will return to normal…
What about some sort of seal that is agressive that has blade like fins, goes on land, and sticks on your base/cyclops and breaks in and attacks you once you enter (it will give you a hull breach and can easily be killed)?