OK, so you've heard of (and maybe visited) the likes of The Grand Canyon, Niagara Falls and Redwood National Park – but the USA has plenty of natural wonders that fly under the radar. If you’re looking to escape the tourist crowds and experience the country’s raw beauty like a local, we’ve ranked the most overlooked natural attractions that deserve a spot on your bucket list. 

Click through the gallery to discover our pick of the USA's lesser-known natural wonders...

Niagara Falls may be better known, but at 212 feet (65m) tall, Shoshone Falls is even taller than its more famous cousin which is 188 feet (57m) high. Nicknamed ‘the Niagara of the West’, these thundering falls are located on Snake River in Twin Falls and carve their way through a deep basalt canyon to Columbia River. Despite being relatively overlooked these days, it wasn’t always so – tourists visited Shoshone Falls as early as the mid-19th century. Travellers along the Oregon Trail would detour just to take in the epic cascades.

Despite its epic size (it covers 13.2 million acres) and beauty, Wrangell-St Elias National Park and Preserve gets surprisingly few visitors. Around 67,000 people venture here every year – so you have a good chance of getting America’s largest national park to yourself, bar the odd bald eagle, moose or mountain goat. It's packed with natural wonders. From volcanic peaks and ice fields to the impressive Kennicott Glacier (pictured), which is sadly losing six to 23 feet (2 to 7m) of ice every year due to global warming, there's plenty to see here.

Oregon is crammed with natural wonders you’ve probably heard of, such as Crater Lake, The Painted Hills and Columbia River Gorge. But how about Haystack Rock? Towering 235 feet (72m) above the sand, this huge monolith is located at Cannon Beach in Clatsop County. It was formed by lava flows from the Blue Mountains and the Columbia Basin, which also created other sea stacks along the Oregon coast. Look out for starfish, green anemones, crabs and corals in its tidepools, and puffins nesting above.

When it comes to California’s natural wonders, Yosemite and Death Valley steal the thunder of McArthur-Burney Falls which is located at the heart of Shasta County. Named after pioneer settler Samuel Burney, the majestic falls were once dubbed the 'eighth wonder of the world' by President Theodore Roosevelt – and you can see why. At 129 feet (39m), it’s not the state’s highest waterfall but it's arguably its most beautiful.

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Just outside Gainesville, this prehistoric spring is a natural wonder that’s almost hidden from view. Located underground, inside a dry cave that’s home to extinct fossils, it’s fed by an underground river and its crystal-clear water is geothermically warmed to a balmy 22°C (71.6°F). The water is so warm that on cold days, you can see steam rising from the cavern’s opening like smoke. This eerie view led the early settlers to compare it to hell, giving it its current moniker. Today, it’s a top scuba diving and snorkelling site. 

Only accessible to the public by water, Turnip Rock may be a small geological formation, but it leaves a mighty impression. Jutting out of shallow waters close to Lake Huron's shore, the unusual stone stack was shaped by strong waves crashing against the bottom. This caused some of the lower sections to erode while leaving the ‘turnip’ top untouched. Although it’s located on private property, it can be viewed by kayak or canoe via a scenic seven-mile (11.3km) out-and-back paddle from Pointe aux Barques.

The Grand Canyon might steal the limelight in this state, but don’t forget about Devil’s Bridge when you're in Arizona. Located in Sedona, more than 100 miles (160km) south of the world-famous chasm, this rock formation is also awe-inspiring but gets fewer crowds. The 1.8-mile (2.9km) round-trip hike to the top of the natural sandstone arch is fairly short but involves a steep climb.

You may associate Florida’s natural wonders with the sprawling Everglades National Park or Okeechobee, its largest lake. But beneath the waves lies another special bit of nature – the only coral barrier reef in the continental United States. Stretching some 360 linear miles (579km) from Dry Tortugas National Park to the St Lucie Inlet in Martin County, it’s the world’s third largest living coral barrier reef and is protected by the Florida Keys National Marine Sanctuary. It’s home to more than 6,000 animal species, including rays and parrotfish.

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Conditions have to be just right to see the feature that gave this distinctive stretch of shoreline its name. At low tide, at the northern end of Schooner Gulch State Beach, it appears as though hundreds of bowling balls have been rolled out to sea and become wedged in the sand. The geological wonder is the result of decades of erosion and 'concretion', where sediment clumps together to form larger rock formations, in this case sandstone spheres. When the tide rolls in, this congregation of rocks is once again veiled by the sea.

Located along the western boundary of Lake Superior, these sea caves are ancient formations shaped by water and ice. The red sandstone has been carved by the elements into delicate arches and vaulted chambers. In the frigid Wisconsin winter, dramatic giant icicles form inside them. It’s the only time of year when they’re accessible by foot, so it’s best to visit in February when the lake’s ice is usually at its thickest and safest to walk across. In warmer months you need a kayak to explore the caverns up close.

This kaleidoscopic geyser in Nevada’s Black Rock Desert is a natural wonder that was created accidentally. In 1964, a geothermal power company drilled a test well here. They failed to properly seal the opening they made, and scalding hot water proceeded to shoot 16 feet (5m) into the air. Today, the geyser still spews water and steam. The brilliant colours you can see are formed by the algae that covers it. Calcium carbonate deposited around the water jets has turned into three large mounds and the geyser is now six feet (1.8m) tall.

Oregon is best known for its lush green landscape – which is partly what makes this stark desert so underrated. The wide-open expanse is a dry lakebed that gets just seven inches (17.7cm) of rain every year. The lake’s water evaporates over time, revealing ghostly pale, cracking alkali beds. Also known as the Alvord Playa, the fractured earth is best viewed at sunset, although the backdrop of mountains and natural springs makes it special at any time of day.

For glaciers that are relatively under the radar, head to North Cascades in Washington state. Montana’s Glacier National Park may often be ranked among the top 10 most-visited US national parks, but around 500 miles (805km) away, this national park has a similar landscape – but blissfully, fewer crowds. It features more than 300 glaciers (compared with the now 25 or so surviving ones in Glacier National Park), including the epic North Klawatti Glacier. 

You don’t have to visit the Grand Canyon to witness an awe-inspiring red-rock landscape. Formed by millions of years of water erosion, the lesser-visited Palo Duro Canyon may be smaller than Arizona's famous chasm, but it’s crammed with an equal amount of beauty and epic vistas – with more room to take it all in. Located 25 miles (40km) from downtown Amarillo, it features 16 miles (26km) of paved road, plus rugged hiking and biking trails.

Crowds flock to the vantage points at Niagara Falls – in fact, it’s thought that around 22.5 million visitors head there from both sides of the US-Canada border every year. Thankfully, the cascades at Letchworth are quieter. Only a couple of hours’ drive from Niagara Falls, these cascades are mighty impressive – at their highest, the waterfalls reach 600 feet (183m) and are backed by lush woodland. The park can get busy in summer, so head here in late fall or even winter for the best chance of having it to yourself.

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The Everglades may be one of America’s natural treasures, but that means they can also feel a little too obvious an attraction. Instead, head further north to Big Cypress National Preserve. It’s free to enter, and it's also packed with wildlife. In fact, visitors frequently claim to spot more wildlife here than in the Everglades. See alligators beneath your feet at the visitor centre’s observation deck – or simply take in the majestic cypress forests that give this pretty spot its name.

OK, so it may not be massively ‘hidden’, sitting in one of the USA’s biggest national parks, but Yellowstone’s Castle Geyser is often overlooked in favour of its more famous sister, Old Faithful. Equally impressive yet drawing fewer crowds, cone-shaped Castle Geyser is larger and older, though it erupts less frequently. When it does get going though, you can expect to see quite a show. The water shoots up to 90 feet (27m) in the air.

Believed to be around 10,000 years in the making, this unique swimming hole is tucked away in Heber Valley, in Midway, northern Utah. Hidden by limestone rock, the geothermal spring waters are a toasty 35°C (95°F). From the hole at the top, natural light spills through to the water 65 feet (20m) below. Master scuba diving, explore the place with a snorkel or simply wallow about in the geothermal waters.

Straddling the border between Texas and Louisiana, there’s something otherworldly about marshy Caddo Lake. Some of the cypress trees that give the lake its signature bayou appearance are over 300 years old. Take to the swampy waters in a kayak or canoe, and see the trees up close, draped in Spanish moss. Look out for alligators basking on logs, and herons, armadillos and turtles on the banks.

Off the coast of Oregon, Thor’s Well is a unique watery spectacle. Sometimes referred to as the 'drainpipe of the Pacific' or even ‘gate to hell’, it’s actually a gaping sinkhole in the Cape Perpetua Scenic Area. It's believed that it was once a sea cave, before the roof collapsed and the bubbling well was formed. Although it’s only 20 feet (6m) deep, it’s as powerful as it is beautiful and will swallow you whole if you venture too close. At high tide, it violently spits out sea water 40 feet (12m) in the air. Take your photos from the shore. 

Located near the aptly-named Sweetwater in Tennessee, Craighead Caverns is an extensive cave system, which contains America’s largest underground lake, the Lost Sea. Used since the days of the Cherokee Indians, this little-known subterranean wonder is now a fun family attraction with knowledgeable guides sharing stories of its fascinating history on walking tours. You can also take a boat ride on the four-acre lake, which lies some 140 feet (42.6m) below the ground.

Ever wondered what the world’s largest musical instrument looks like? You’ll discover it at Luray Caverns in northern Virginia. Here, a stalactite (or 'Stalacpipe') organ makes ethereal music by gently knocking on the surface of hanging stalactites. There are also vast echoing chambers and towering stone formations to discover. Another highlight here is the so-called Dream Lake – a shallow body of water that dramatically reflects its surroundings.

It may be less than two hours from both Denver and Colorado Springs, but this geological wonder still flies relatively under the radar. Spanning 750 acres, the ancient site has evidence of human life going back 9,000 years. There's also tall, thin spires and gullies formed by thousands of years of erosion. Oxidised iron compounds caused the colourful bands evident here to emerge. The park is named after these vibrant coloured clays that were mined by American Indians to make paint.

The name makes it sound almost sinister, but this landscape dotted with petrified wood (wood turned to stone) looks almost too beautiful to be real. Stretching across miles of Interstate 40 in the north of Arizona, the national park has two standout natural features. In the north, the Painted Desert is a series of striped, multicoloured hills formed over millions of years; in the south you’ll find those petrified trees, a collection of stunning fossilised logs filled with quartz crystals.

We bet you’ve heard of Kentucky’s Mammoth Cave National Park – but what about its Lost River Cave? Located in Bowling Green, this underground river and cave also has a fascinating history – it’s been everything from a nightclub to a Civil War camp. It was used by aboriginal Americans as a shelter and water source, and was later converted into a sawmill. You can explore the cave on an underground kayak tour or stay on land and hit the surrounding nature trails.

Compared to Utah’s famous Arches National Park, the orange structures of Natural Bridges National Monument are an overlooked natural wonder. And yet, they are almost carbon copies of the features in the better-known red-rock wonderland. Around 100 miles (160km) south, Natural Bridges still features incredible rock formations, carved out by rivers over millennia. The three bridges are named Kachina, Owachomo and Sipapu after the ancestral Puebloans who once lived here. This was also the world’s first International Dark Sky Park.

Wild and inhospitable, the Bisti/De-Na-Zin Wilderness is a rolling landscape of badlands that can’t be fully accessed by road. They're ideal for hardcore hikers looking to escape the crowds. Once a river delta, this area has topography like you’ve never seen. When the water receded from these parts, it left behind bizarre rock formations made of sandstone, shale, mudstone, coal and silt. There are pinnacles, spires and mushroom-shaped rocks, caused by weathering over the millennia. With little shade, no water sources and searing summer temperatures, a day out here is for the hardy.

The Golden State is packed with natural wonders so this fascinating geothermal area is often overlooked – but it shouldn’t be. Located in Lassen Volcanic National Park in northern California, its blue and yellow pools resemble the famous Grand Prismatic Spring in Yellowstone. You can hike a three-mile (4.8km) trail here to take in the whistling steam vents and simmering mud pots. The area was discovered in the 1860s by cowboy Kendall Vanhook Bumpass – he labelled it 'hell' after losing his leg by breaking through thin crust above a mud pot. 

In Arizona, most tourists seeking undulating sandstone walls head straight to Antelope Canyon. But, a mere 20-minute drive east, Waterholes has a similar appearance, with a warm orange glow on its rugged exterior. And the best part is that its comparative anonymity means you can explore it without the crowds of hikers and budding photographers you’d meet at the better-known version up the road. To visit, you need a permit from the Navajo Nation Parks and Recreation organisation.

Our pick for the number one overlooked natural wonder in the US? New York's sunken forest. Only a short distance from the throbbing crowds and landmarks of New York City, Fire Island couldn’t feel more different. Reached via a ferry from Long Island, the forest takes its name from the sand dunes that tower up around it, partially hiding it from view. Penetrated by an elevated boardwalk, the 1.6-mile (2.6km) nature trail zigzags round the rare ecosystem of 300-year-old American hollies, shadbush and black cherry trees.

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