Spelunking (noun)

1. The activity of exploring caves and caverns.
2. The exploration of caves and underground caverns as a hobby or sport.

Origin:

The word "spelunking" comes from the american english and is derived from the word "spelunker" which is a person who explores caves, it refers to the activity of exploring caves and caverns.

Examples:

1. Spelunking is a dangerous but exciting hobby.
2. He was an experienced spelunker and led the group into the cave.
3. Spelunking requires special equipment and training.
4. The group went spelunking in the limestone caves.
5. The park offers guided tours for spelunking.