The Lost Caravel of One-Eyed Wilhelm
(Key word: lost)
The notorious One-Eyed Wilhelm established a hideout for his pirate crew inside a seaside cave. Several living quarters, a mess, and an animal pen comprise this vile settlement, nestled against a cliff.
The cave is deep, and just large enough to navigate the caravel.
One-Eyed Wilhelm and his crew returned to port, the ship heavily laden with treasure of all types, both mundane and magical. No sooner had they anchored, an earthquake struck. The quake brought down enough of the cliffside to completely seal this cavern. Fifty years have since passed; if anything yet moves on the boat or shore, it is undead.