The practice or hobby of exploring underground caverns.

present participle of spelunk

plural of spelunking

(obsolete) A cave, cavern or grotto.

To explore caves. / To explore a system in depth.

(Canada, US) One who explores caves; one who spelunks. / (derogatory) An amateur or inadequately prepared caver.

Third-person singular simple present indicative form of spelunk

simple past tense and past participle of spelunk

plural of spelunker