A famous French speleologist, Norbert Casteret, described going into a cave as leaving the world he knew—of bird songs and blue skies—for a mysterious world of blackness filling him with mystical enthusiasm.

Will you see a mystical place when you enter a cave? Or a smelly, dirty, guano-filled hole infested with bats? What you see in a cave is up to you.

Select a topic to find out more about cave environments.