Hur,” “The Wizard of Oz,” TV shows, props and costumes can be found 650 feet underground in a Hutchinson salt mine.

From health spas to film storage, salt mine caverns have been put to use in surprising ways—and they’re now poised to contribute to the generation and storage of clean energy.

Wieliczka, Poland (CNN) — Down at the bottom of 380 dizzying steps, the walls are an imperfect gray. They look like rock — but they taste salty. How do visitors know? They’re encouraged to lick them.

Rain clouds had been following us all around Poland, and so we doubled the usual tour of castles, cathedrals and museums.

An underground salt deposit in Queensland could prove to be the perfect place for hydrogen gas or compressed air. A ...