Wild lights and sound effects turn a walk through some caves into an eye-popping 1960s tourist attraction.

Climb right into the heart of this colorful Iceland volcano.

These delicate sand pyramids look like naturally occurring gothic spires.

The caldera of this mini-volcano has been turned into a naturally heated mud bath.

This stunning concert hall has become a symbol of Iceland's national recovery.

One of the most remarkable caves in all of Iceland was created by a once raging river of lava.

A turquoise lake within a volcanic crater.

A steaming, boiling hellscape sources Hokkaido's thermal baths.

Submerged busts of communist and socialist figures from the USSR.

Submerged trees jut ghost-like out of an idyllic turquoise mountain lake.

Each year melting snow turns these Austrian hiking trails into scuba zones.

A cemetery and the town it served sinks beneath the sea during the volcanic birth of Mt. Vulcan.

Bohol's mysterious brown hills.

A magically clear, blue river that seems to spring from nowhere.

A public park off the beaten path with a beautiful waterfall and 13th century Cistercian abbey.

This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

The remains of the last Bosnian fortress to fall to the Ottomans are still standing.

What looks like a link in Gondor's early warning system is actually a centuries-old Italian fortress.

This fortress in Honduras was built to resist pirates, but its builders had more to fear from the British.

A large collection of motorbikes with some impressive gems.

The Icelandic Sea Monster Museum explores the area's history of aquatic cryptid sightings.

This portion of a lovely Belize beach is infested with (harmless) sharks and rays.

This collection of historical artifacts and tropical wildlife waits just beneath the surface of the water.

A massive underwater sinkhole made famous by Jacques Cousteau.