On the flip side, his people can't really do anything on land.

Though I do find it kinda strange that it's been so long and they've never met a single person from the surface. I mean, I'm certain people have been fishing in their waters for centuries.

EDIT: Wait... What are those spears made of? I can't see the people having invented metal forging and I can't see a bunch of bone/stone spears managing to tear sizable holes in a ship's hull that easily.