I'm a big fan of pirate-themed adventures and this one is solid!
The map looks fantastic. It could be a little easier to read if the walls were drawn with slightly thicker lines to help them stand out. With the mention of the natural chimney, I find myself wondering what the island above the grotto is like. It would be nice to have even a couple bullets for direction on that, plus some indication of the terrain going up from the beach or ocean entrances. Otherwise, there's no direct way for a GM to make use of that alternate chimney entrance.
There's lots of things for players to interact with here and it's all described clearly so a GM could run it with minimal prep. The traps, castaways, organ encounter, and statue are great. I do wish that the encounter with Captain Marrow was presented with a roleplay / non-combat option, however. My favourite ghost encounters usually involve some kind of mystery or unfinished business that the players can engage with. A lot of the fun of ghosts comes from letting the players have something to solve (such as an unexpected love story, seeking justice for a secret crime, returning something that was stolen, etc.), instead of just a combat slog. I also wonder if it would be fun to add a brief ghost haunting to the encounter table (even as an alternative light extinguisher to the tidal waves) to make things more cohesive.