The first declared National Monument in the United States.

A waterfall 600 ft. inside a mountain, once the bane of gold miners, is now a spectacle of nature.

Calidum et Deliciose Succosum!

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

Where the famed daredevil attempted to launch himself across a canyon in a custom-built rocket.

These falls, sometimes called the "Niagara of the West," still put on a good show at the right time of year.

Home to a timed geyser created by complete accident.

Nature has shaped this drainage tunnel into the digestive tract of a mighty beast.

This magnificent natural sandstone bridge is one of the largest in the world and is an iconic symbol for Lake Powell.

The damming of the Colorado River buried an iconic geologic formation before record-breaking drought brought it back.

This ancient cave is home to a museum, bar, and is filled with fluorescent minerals.

An earthwork sculpture built by Robert Smithson in the Great Salt Lake only reemerges during drought.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

Dig for your own trilobites in this goldmine of invertebrates.

Hundreds of painted rocks dazzle this small beach where adding your own is encouraged.