So this is gonna be a bit of a difficult one but I feel serpents are not that scary late game and going out in a boat other than the first one it's already easy enough to deal with them. The Kraken would appear as a maelstrom in the deep ocean. It would be easy to dodge if noticed but anyone not paying attention would soon be at a difficult battle. The mouth would be seen in the center and the water would be near impossible to swim out of. Tentacles could be shot at the boat in an attempt to take it down so you float into the center. Obviously, if that happened you would die and retrieval would either have to be impossible or there would have to be some way to kill it. The odds of the Kraken appearing would be slim. Not an impossible encounter because you can intentionally or accidentally sail into it, but also not an easy to avoid one once you're in it. I guess maybe if you sail into the middle of it but slightly off to the side, you can pick up enough speed to steer out of it assuming the tentacles don't get you first. I'm just hoping for something to make the ocean better if the scariest thing in it isn't even scary by the swamp biome.