A lake at the bottom of the ocean.

Underwater art project will double as a massive artificial coral reef to help regenerate the damaged ecosystem.

One man's fulfilled dream of living on an artificial island made of recycled plastic bottles.

In the middle of this historic colonial city resides a modernist government building known as the UFO.

The walls of a colonial-era fort encircle a small, tropical assortment of plant life.

Few of the many visitors to this resort town know of its hidden Maya ruins.

An ancient system of freshwater caves filled with animal bones, including that of species long-extinct.

Cave where bat-eating snakes hang down from the ceiling.

A flooded Mexican cave that hides a river beneath the water.

Once a year in Pomuch, the dead are taken out for a cleaning.

It would take you approximately an hour and a half to walk to the end of Mexico's largest pier.

One of the few places where you can visit a cenote and Maya ruins at the same time.

This popular cave pool is truly magical, despite the crowds.

If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

Found down a long dirt road, a sacred Mexican cenote and 18th-century hacienda remain hidden.

These azure waters were thought to lead to the Mayan Underworld.

A field of whimsical floats, where all of your favorite childhood stories have been put out to pasture.

Its sunny hues are believed to have inspired the town's color palette.

Three sinkholes filled with warm, crystal-clear water reached by a horse-driven cart on an old train track through the jungle.

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Fish raining from the sky are the cause of a yearly celebration in this small Honduran town.