A spring-fed pool so deep it's used for scuba diving as well as swimming.

Once defending the city of New Orleans from invasion by sea, this fort faces an uncertain future.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

A tourist attraction founded around a slumping cabin.

Only known mainland rookery of the threatened Stellar sea lion.

On a barren hillside in the Yucca Valley, the recently restored Desert Christ Park has attracted pilgrims and kitsch hunters for over 50 years.

A crumbling Beaux Arts monument to the Bay Area's age of rail.

An obscure waterfall that looks like something out of a fantasy novel.

An apocalyptic seismic event creates a deadly chain reaction that ends with a 6-mile long lake developing within weeks.

The oldest continuously operating church in California.

Fake rail crossings mark the site of an influential doctor's demise.

Steinbeck's old stomping grounds, immortalized in Cannery Row.

The second oldest continuously operating bar in Louisiana.

A hotel and restaurant serving as the mecca of kitsch.

A massive volcanic plug is now a protected area that hosts a number of bird species.

The world's first permanently occupied mountain-top observatory continues to report on the stars.

The liveliest ghost town in the state.

Oldest building in California still in use.

A museum of unusual collections, mini-towns, and a half-dog, half-alligator.

Megachurch turned Catholic church comprised of 10,000 glass panes.

Decommissioned experimental solar facilities that pioneered solar energy technology.

Abandoned Air Force base that has fallen into disrepair.

The "world's biggest dinosaur" once housed a creationist museum in its abdomen.

Costumed elves and mountain bikers co-exist peacefully at this abandoned Christmas-themed adventure park.