That cover is, of course, immaculate.
A great cursed weapon as well, good enough that even rational players will be tempted to keep it around if they're "sure" they can handle it.
Gotta love a talking partial skeleton.
Fantastic magic items.
My only critique is that I'd like the map to be less of a tunnel and offer players more than one choice how how to move through the caves.
Otherwise, this is a great adventure. I could definitely see using this with Pirate Borg, where it'd fit in great.