>>727691
Caves make excellent shelters. You've just got to make sure you're not the only one with that idea before you move in, though.

why spend all that energy building a shelter when he had that sweet cave?

PrimTech:
>shit no cave
>i must build one myself then

CastAway:
>ooo cave
>take a nap

PT isn't inventing shit on the spot, he is using documented knowledge that you can study in books.
Castaway didn't have access to a library of research on old technology.

He basically had rocks and sand. It's a desert island. Caves are generally thermo-regulated so that was his best bet for a long-term shelter.