The largest drain hole in the world.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

Friction between grains of sand cause a curious "singing" sound.

This modern medieval weapon of war was built to toss pumpkins.

This locally-famous crevasse in New York State is icy all year round.

Don't be a grizzly man. Get personal with Alaska's wild bears from the safety of this conservationist camp.

A rare kind of blue bear can be found chiefly in the national park that shares their name.

A desert ghost town—occupied for only 12 years—was once home to more than 500 silver mines.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

This pebble beach is so beautiful that taking its rocks is against the law.

Research missiles and rainbow auroras at the world's largest land-based rocket range.

This narrow canyon has been carved by the river over thousands of years into spectacular and curious forms.

Bubbling up from deep underground is the warm crystal clear water that fills the Warm Springs Pools, America's oldest spa.

This unusual lava tube spouts seawater during high surf.

Half of a waterfall goes into the river while the other half seems to disappear.

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

When waves crash onto this section of beach, the rocks sing a song.

Curious cave that stays a cool 56 degrees all year long.

An unexpected but incredible collection of wildlife dioramas spanning rainforests, swamps, forests, and plains.

This angular Dwarven tunnel cuts through a mountainside in Glacier National Park.

An extraordinary mixture of natural beauty and man-made phenomena.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

Oregon's unexpected high desert, displaying layers of time in a colorful show.