A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

An emerald-green grotto just a short trip from Austin.

On Japan's Tashirojima Island, cats are king.

This series of rope-style bridges brings visitors into a jungle layer that is usually reserved for birds and monkeys.

Island of trash twice the size of Texas floats in the Pacific.

After an epic flood washed away its enslavers, this city has been part ghost town, part cultural wildcard for the past three centuries.

An earthwork sculpture built by Robert Smithson in the Great Salt Lake only reemerges during drought.

A seemingly endless landscape of pure salt stretches far across Bolivia.

A cabin completely covered in coffee mugs, where visitors are welcome to leave one of their own—if they can find an empty nail.

A hand-built folk art installation covered with messages of God's love.

Theme park featuring miniature replicas of European monuments.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This lab's maddening silence is good for business but bad for sanity.

A giant bronze coil of feces is both a tribute to doggie defecation and a reminder to pick it up.

A little-known subterranean street runs under some of the best-known buildings in Chicago's River North.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

Secret Swing.

San Francisco Bay's ghost town.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.