Nature

This dilapidated castle-like structure overlooks the Hudson River at one of its widest points and was once home to nuns.

Bohol's unusually shaped hills turn brown in the summer months.

They squeal, they nosh, they look like predators.

A maritime museum holding the remains of Blackbeard's pirate ship.

A stratovolcano located in the south of Iceland, with a long history of charted activity and a rich mythology attached.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

Largest cave system in Africa.

A curious blend of taxidermy, antique tools, creationism, and a purported antediluvian rock.

Limestone caves with spectacular showcase chambers.

An island in the middle of a lake, in the middle of a volcano, in the middle of a bigger lake, in the middle of a bigger island, in an archipelago, in the Pacific Ocean.

A wonder of natural limestone formations etched by millions of years of natural interaction between rainfall and rock and air.

Every autumn, this hillside is ablaze with red summer cypress.

The youngest volcano in Central America.

First a horse rendering plant, then a 19th century landfill, this beach is full of glass from thousands upon thousands of broken bottles.

An Australian lake whose pink hue defies scientific explanation.

A lake in the middle of the tundra of Quebec is said to be the purest freshwater lake on Earth.

One of the final concrete ships built before World War II is now a crumbling breakwater.

Millions of glowing microscopic organisms light up the waters of this luminous lagoon.