An abandoned asylum incorporated into a college campus.

The perfectly named cave drop is the deepest in the continental United States, almost matching the height of Seattle’s Space Needle.

Rare recess caves fill this unbelievably beautiful Ohio park.

This Big Sur waterfall drops 80 feet directly into the Pacific Ocean, and inspired the hillside house up top.

The site of murders and Satanic cult gatherings.

Canyon walls shrouded in ferns.

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.

This strange seaside tower got its name from a wealthy eccentric who would hide coins among its stones.

The highest point in Arizona is an oddly snow-topped peak within the otherwise arid state.

Limestone caves with spectacular showcase chambers.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

Most-visited and most-photographed slot canyon in the American Southwest.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

148 feet long and in the middle of a verdant forest.

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

A rugged lava field dotted with molds of the ancient pines that were growing when the volcano erupted.

The first North American landing spot for James Cook on his third voyage of discovery in the Pacific.

A volcanic fissure over two miles long and up to 70 feet deep.

A massive sea stack famous for its appearance in The Goonies.

Only known mainland rookery of the threatened Stellar sea lion.

The longest continuous lava tube in Oregon.

Lions and tigers and leopards, servals, pumas, bobcats, lynxes, and ocelots... oh my!

Rustic natural hot springs in the deciduous rain forest.

Hollowed out cedar log tubs set in an ancient towering forest.