A luxuriant botanical garden below sea level.

A marvel of Byzantine engineering under the streets of Istanbul.

Hidden just under the waters around this Turkish island are the ruins of a once great city.

Half-drowned wooden stumps and stone blocks are all that remain of a Victorian landing that was destroyed by storms.

A submerged archeological park still holds the wonders of a Roman Sodom.

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

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

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

Self-mummified monk who wears sunglasses and has become a gecko hatchery.

This floating cinema brings new meaning to the phrase "going out" to the movies.

This dangerous-looking suspension bridge may have been too unstable to remain open.

Colorful umbrella-covered trees in Singapore's Little India look straight out of Dr. Seuss.

Singapore's landscaping project is home to 18 incredible Supertrees.

The most playful of the life-sized statues that make up Singapore's "People of the River."

A Singapore shrine to an unnamed German girl who has become a local deity.

Terrapins of all colors and shapes are quick to bring fascination (and possibly long life) at this museum.

One of the largest caverns in the world has a maw large enough to stack cathedrals in.

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

This mysterious underground cave in Shropshire dates back to the 18th or 19th century.

A swing to dangle you off the very edge.

Stalactites and stalagmites in a beautifully lit cave.

Virgil's many-mouthed gateway to the underworld.

A massive underwater sinkhole made famous by Jacques Cousteau.

Sparkling, calcite-covered skeletons of children who may have been sacrificed to appease an angry god.