Explore the ancient caves of Hang Son Doong, Vietnam. Hang Son Doong is one of the largest caves in the world and features a fast-flowing underground river. For spelunkers, exploring Hang Son Doong is the equivalent of scaling Mount Everest.
I'll have one of these in my beach house, thanks! Geo 180 Round Bath With Rain Shower! Awesome ♥ Modern tub by Kos of Italy combines a whirlpool option with a cascading ceiling mounted shower head that doubles as a soothing mood light.
Ice cave in the Skaftafell National Park in Iceland. Ice caves collapse and new ones form as each glacier grinds slowly towards the sea. Local guides can help you (without dying) find one. (Visit Skaftafell National Park in Iceland.