Spelunking is an activity that involves exploring caves and other underground areas. It is a popular recreational activity, as well as a scientific pursuit. Spelunkers often use specialized equipment such as helmets, headlamps, and ropes to navigate the dark and often dangerous underground environment. The term 'spelunk' is derived from the Latin word spelunca, which means 'CAVE.' Therefore, the crossword solution for the term SPELUNK is CAVE.