Answer: spelunk

AnswerCrossword Clue
SPELUNKGo caving
SPELUNKParticipate in some underground movement?
SPELUNKExplore caves
SPELUNKChart caves
SPELUNKExplore among stalagmites and stalactites
SPELUNKCave
SPELUNKGo below, in a way
SPELUNKExplore in the dark, perhaps
SPELUNKDo some underground exploring
spelunkto explore caves, especially as a hobby.
spelunkto explore caves