The steaming, multicolored circle of the Grand Prismatic Spring is one of the most hypnotic and unique sights in the U.S. Part of Yellowstone National Park, this hot spring is the largest in the country and the third-largest in the world, measuring 370 feet wide and 160 feet deep.

Its vibrant colors, ranging from deep blue in the center to fiery red and orange at its edges, are unlike anything we see in nature every day. Minerals and microbes are responsible for these hues, with water temperature causing the pigments to fluctuate. The spring owes its existence to geothermal activity driven by Yellowstone's underlying magma chamber and is located in the Midway Geyser Basin.

Image: MikeGoad

One of the reasons why Fly Ranch Geyser is unique in the world is that it was formed after a human accident. This technicolor geothermal geyser, located on the Fly Ranch property in the Hualapai Geothermal Flats of Washoe County, Nevada, wasn’t there before 1916.

In 1916, while drilling a well for irrigation in the area, workers struck near-boiling geothermal water, leading to the creation of the first geyser. Decades later, in 1964, a geothermal energy company drilled a second well nearby, which caused the emergence of the Fly Geyser we know today. It has been spouting water into the sky ever since, forming several cone-like vents atop a mound that continues to grow.

Image: Ken Lund, CC BY-SA 2.0

Where does the water from the Brule River go when it falls? For a long time, this was a mystery. Located in Judge C.R. Magney State Park near Grand Marais, Minnesota, along the North Shore of Lake Superior, the river is famous for its unusual split: one half flows downstream, while the other plunges into a seemingly bottomless hole.

This waterfall has baffled visitors and scientists for years because objects thrown into the "kettle," such as logs and ping-pong balls, appeared to vanish without resurfacing. This fueled theories of underground rivers or deep caverns beneath the falls. The mystery was solved recently when hydrologists discovered that the water entering the kettle resurfaces downstream. The kettle's strong currents explain why objects thrown in don’t resurface; they are broken apart and held underwater, functioning like a natural washing machine.

Image: chrishawaii

These unique limestone formations, known as the Mono Lake Tufa Towers, emerge from the salty, alkaline waters of Mono Lake, fed by underwater springs. Located in eastern California, near the Sierra Nevada mountains and about 13 miles east of Yosemite National Park, they are a striking natural wonder.

These tufa towers rise dramatically from the water. How were they formed? Mono Lake has no outlet, so its high alkalinity and salinity caused minerals to accumulate over time. This unique environment supports an ecosystem of brine shrimp, alkali flies, and migratory birds. To give you an idea, the lake’s salinity is more than twice that of the ocean, which means you could float effortlessly in its waters, as many visitors do.

Image: Stephen Leonardi

If you find a diamond here, you get to keep it—this is the only diamond-bearing site in the world where that's possible. Open to the public for mining, the Crater of Diamonds is a 37.5-acre field located near Murfreesboro, Arkansas. It marks the eroded surface of a volcanic pipe composed of lamproite, a rare volcanic rock.

Visitors sometimes find diamonds of various colors, including white, yellow, and brown, along with other gems like amethyst and garnet. It was here that the "Uncle Sam Diamond" was found, the largest diamond ever dug out in North America, weighing 40.23 carats. Diamonds were first discovered here in 1906 when a local farmer found unusual crystals on his land, which sparked a minor diamond rush.

Image: Brett Sayles

Rocks that look like flowing water: Antelope Canyon is a famous and breathtaking slot canyon in northern Arizona. It consists of two main sections: Upper Antelope Canyon (a.k.a. Tsé bighánílíní, or "the place where water runs through rocks") and Lower Antelope Canyon (Hazdistazí, or "spiral rock arches").

The canyon was formed over millions of years as flash floods and desert winds eroded the Navajo Sandstone. Even today, seasonal flash flooding continues to shape and carve the canyon’s mesmerizing features. Its surreal, wave-like formations in shades of orange are a favorite subject for photographers and tourists from all over the world.

Image: Roberto Lee Cortes

The Petrified Forest National Park in northeastern Arizona boasts one of the world's largest and most vibrant concentrations of petrified wood. The park, part of the Painted Desert, is located between the Apache and Navajo Counties.

Most of the wood found there is from ancient conifer trees that date back about 225 million years to the Late Triassic period. These trees were swept into river systems, buried by sediment, and transformed into stone through a process called permineralization. The park also features a wealth of fossilized remains of ancient animals, including early reptiles.

Image: Megan Clark

The Devils Tower stands alone, protruding dramatically from the plains. Considered sacred by Native American tribes, it was originally called "bad god’s tower," a name that eventually evolved into its current form. Located in northeastern Wyoming, this igneous rock monolith soars 867 feet above its base.

It was designated the first U.S. National Monument by President Theodore Roosevelt in 1906. Geologists agree that Devils Tower was formed through the intrusion of magma into sedimentary rock layers about 50 to 60 million years ago. Today, climbers from around the world are drawn to its sheer walls, though climbing is prohibited in June to honor Native ceremonies.

Image: Kyle Petzer

The Wave is a visually stunning sandstone formation located in the Coyote Buttes North area of the Vermilion Cliffs National Monument. Known for its hypnotic, swirling bands of red, orange, and yellow, its delicate ridges are so easily damaged that even one misplaced footstep could ruin the beautiful patterns.

Approximately 185 million years ago, this area was a vast desert covered in dunes. Over time, layers of sand were deposited, compacted, and cemented, forming this Navajo sandstone shape. Unfortunately, The Wave is only accessible by a challenging hike that requires a permit, due to the fragility of its ecosystem and high demand from visitors. With less than 5% of applicants obtaining a permit each year, it is one of the most exclusive hiking destinations in the world.

Image: Mark Nemenzo

The Kasha-Katuwe Tent Rocks National Monument, located in northern New Mexico, displays a unique landscape of tall, cone-shaped rock formations. These "tent rocks," composed of pumice and tuff, are known as "hoodoos." They are natural formations ranging from a few feet to approximately 90 feet tall.

The name "Kasha-Katuwe" means "white cliffs" in the Keresan language of the Cochiti Pueblo. Hiking trails, such as the Slot Canyon Trail, offer visitors the opportunity to explore the cones up close while walking through dramatic, narrow canyons.

Image: Bruce Warrington