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

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

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

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

Rippling sand dunes frozen in the Arizona rock.

A museum devoted entirely to hammers has more than 1,400 items on display dating back to the Romans.

Siberian husky that delivered a life-saving antitoxin.

Research missiles and rainbow auroras at the world's largest land-based rocket range.

During the summer, surfers in Alaska take advantage of this inlet’s unusual water patterns.

A giant poultry statue immortalizes one of Alaska's more humorous town names.

An auroral research program that superheats the ionosphere.

Internationally recognized group that works to protect the wolf and educate the public about its plight.

A rare kind of blue bear can be found chiefly in the national park that shares their name.

A historic freight system that found the true gold rush is in tourism.

An Alaska livestock farm devotes itself to harvesting wool from creatures that once ran with mammoths and sabertooth tigers.

Low tide reveals 8,000-year-old rock carvings in Southern Alaska.

The "Gateway to the Arctic" connects Barrow's indigenous population with the sea and its traditional industry: whaling.

Massive mounds of golden sand look like a desert landscape randomly plopped in an Arctic forest.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

A trading post in the North Pole where children send letters.

This frozen tunnel in central Alaska is both an engineering feat and a valuable climate classroom.

Gorgeous cave resemble a winter wonderland.

Upside-down trees serve as natural flower pots in this hanging garden of Alaska.

This whimsical stacked cabin looks like something out of a children's book.