The diver.

(He was swimming around in a ocean of the old past world And he swam to a cave that was inhabited by you. a Skeleton like sea monster with sharp thin claws Gills and legs that have Fins and finally you have a human skull you used as a mask. and He was swimming around in your cave trying to look for supplies and he eventually gave up and swam back to his underwater base. and you followed him and got inside his base due to a Tube Under his base leading inside his base. what will you do??)