spelunker

[spi-luhng-ker] /spɪˈlʌŋ kər/
noun
1.
a person who explores caves, especially as a hobby.
Origin
1940-45; < Latin spēlunc(a) cave (≪ Greek spêlynx, stem spēlyng-, akin to spḗlaion; cf. spelaean) + -er1
Related forms
spelunking, noun
British Dictionary definitions for spelunker

spelunker

/spɪˈlʌŋkə/
noun
1.
a person whose hobby is the exploration and study of caves
Derived Forms
spelunking, noun
Word Origin
C20: from Latin spēlunca, from Greek spēlunx a cave
Word Origin and History for spelunker
n.

"a cave bug; one who explores caves as a hobby," 1942, agent noun formed from obsolete spelunk "cave, cavern."