A few older ones come to mind.

Jaws is maybe an obvious one, unless deep ocean is the main priority.

The Abyss is another one, from 1989, directed by James Cameron.

I saw both of them when I was a kid and they were really memorable. I haven’t watched either in several years but I would watch them again. Especially The Abyss.

Less “great” and more “mediocre 1980s slasher with an inaccurate title,” Friday the 13th Part VIII: Jason Takes Manhattan is mostly set on a small cruise ship on the way to Manhattan. I actually hated it when I was younger because of the misleading title, but I watched it again last year and I liked it more. I just had to adjust my expectations that it was actually Friday the 13th Part VIII: Jason Murders The Kids On A Boat. Obviously, the killer is Jason and not an animal, but I thought it was slightly better than it gets credit for.