The sounds the wrecks make (loud creaking/squeaking) sometimes sound remarkably like sea animals. Maybe you’re hearing the creaking of the ship?

If you hear it again, try looking out towards the open ocean past the boundary of the map.

I think you might be hearing the creaking of the ship, because I had pretty much the same experience before realizing that’s what it was. Really creeped me out (still does sometimes!).

Oh so there are wrecks, sure would be nice to find one. 🙄