Answer: spelunker

AnswerCrossword Clue
SPELUNKER

Caveman?

SPELUNKER

Cave explorer: Colloq.

SPELUNKER

He explores caves.

SPELUNKER
One whose hobby is exploring caves.
SPELUNKER
Cave man.
SPELUNKERExplorer of sorts
SPELUNKEROne exploring deeply?
SPELUNKERCave man?