I recently had a conversation with a player about an encounter from a game we played probably around 15ish years ago. The encounter was likely not from an adventure but first-party published somewhere else. The particular scene that we remembered was at an exit from an underwater chute on a small island that the players used to infiltrate some caverns. They encountered undead guarding the chute, who later got back up by casters. The casters used weather control magic to shipwreck the players prior to the encounter.
What encounter was this, and in what book do I find it?