Most American national parks are flooded with visitors in summer, but those who venture out of season will be treated to five free-entrance days at all National Park Service sites in the US in 2023. Visit a park on one of these dates in (16 January, 22 April, 4 August, 23 September, 11 November) and you'll be able to see plenty of natural marvels free of charge. Here's our pick of the best...

The highest point along the North Atlantic seaboard, Cadillac Mountain in Maine's Acadia National Park rises 1,530 feet (466 metres) above sea level. Within easy reach from the charming coastal resort Bar Harbor, the summit is a magical place to welcome the sunrise. The pink granite mountain slopes are clad with pine and spruce forests, with the scenic Summit Road carving its way along the northern and eastern side of the mountain until it reaches the top.

Death Valley National Park, with its stark desert plains and jagged peaks, is scorching in summer, when temperatures climb to 49°C (120°F) in the shade. That means this otherworldly pocket of the southwest is best explored during cooler months. Hiking trails wiggle through the park, passing along canyons, dunes and craters and, come nightfall, the night skies put on a stellar display. The Mesquite Flat Dunes and Badwater Basin are popular stargazing spots.

A popular trek in Zion National Park, The Narrows is aptly-named after the narrowest section of the Zion Canyon, where the Virgin River carves its way through the slot canyon. It's a rather unusual hike as you'll have to wade through water (which can be quite cold during winter). You can also follow a paved Riverside Walk to see this unique natural landmark. The full hike spans 16 miles (26km) but you can also do a shorter 3.6-mile (5.8km) trek from the Temple of Sinawava to Big Springs.

Denali National Park welcomes the most visitors throughout the summer months, but it has charms aplenty in any season. Come September the high-season crowds have dispersed and Denali's trees are ablaze with red and orange, while spring sees the slopes covered in a carpet of colourful wildflowers. The NPS website has a selection of recommended itineraries to explore the park.

This breathtaking wetlands park sprawls across southern Florida and provides a habitat for diverse wildlife, from American crocodiles and alligators to deer and Florida panthers. It supports more than 300 species of bird too. The Anhinga Trail – which wiggles through an area of sawgrass marsh – is a prime route for spotting water birds like cormorants and, of course, anhinga (or water turkeys). Here, two stunning roseate spoonbills are captured in the water.

Big Bend National Park is often overlooked, falling in the shadow of its southwestern sisters. But its shrub-scattered desert and craggy mountains – home to wildlife like black bears and bobcats – keep their charm year-round, and mild autumns and sunny springs are great for hiking. Strap on your toughest old boots and discover trails meandering through limestone cliffs, past waterfalls and around peaks of the Chisos Mountains.

Thousands of years ago, the Ancestral Puebloans built fascinating, labyrinthine dwellings and their ruins are protected within Mesa Verde National Park. Several walking routes wind past the remnants of the largest cliff dwelling in North America, Cliff Palace. Although the Cliff Palace Loop Road is closed for winter (check the NPS website for updates), there's a spectacular viewpoint at Sun Temple on the Mesa Top Loop Road.

Mount Rainier National Park paints a dreamy image: think pyramidal mountains, mirror-like lakes and towering fir trees. One of the best ways to experience the park's majesty is to take in jaw-dropping views of Nisqually Glacier. Nisqually Vista Trail is an easy route with overlooks for the awe-inspiring natural wonder along the way.

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With some of the most dramatic scenery in the country, the Teton mountains are a sight to behold. Grand Teton, the highest mountain in Grand Teton National Park, is one of the top American mountaineering destinations, but don't worry if you're not a climber – there are plenty of ways to view these majestic mountains from the ground. Head to Oxbow Bend to take a brilliant photo of the mountains and spot wildlife like moose, black bears, otters and the occasional grizzly.

In summer, visitors typically jostle for space at the Grand Canyon's South Rim, but this scenic swathe of the national park is open to vehicles year-round – and it's much quieter outside of the sunny months. Hikers will find many trails gloriously deserted, and the hardiest among them can even travel on foot to the North Rim and overnight at a campsite.

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More than 119 caves make up New Mexico’s Carlsbad Caverns National Park. Within this vast cave network, 750 feet (229m) underground, is the so-called Big Room, a chamber so huge it could hold over six football pitches. The caves are home to half a million bats who can be seen swirling out into the night sky at dusk.

Spring and autumn are often one of the best times to spot wildlife in Rocky Mountain National Park. As visitor numbers dwindle, creatures great and small make the most of the quiet wildernesses and forage for food. The park, which folds a spectacular swathe of peaks into its limits, is known for animals like elk, moose and mule deer.

The tall rock spires, known as hoodoos, are the most distinctive characteristic of Bryce Canyon National Park in Utah. Creating a surreal landscape, the hoodoos shine in shades of yellow, orange and red, creating the impression you've stepped onto an entirely different planet. The best way to take in the incredible landscape is to follow hiking trails that lead through the strange rock formations, the forest and around the series of natural amphitheatres.

Late autumn, winter and early spring are the most popular times to visit Saguaro National Park, when the weather is gloriously mild. The main attraction here is the park's namesake – towering saguaros, a type of cactus – which can be seen on various hiking routes. A top pick is the mellow, one-mile (1.6km) Freeman Homestead Trail, which also spools past an old homestead site.

The otherworldly acres of Badlands National Park are as close to the surface of the moon as most of us are likely to get. There are plenty of ways to drink in the landscape, like taking a drive on the Badlands Loop Road, with its various overlooks, including the spectacular Burns Basin Overlook (pictured). Popular routes for hiking include the Door Trail, a straightforward boardwalk loop that offers fantastic views of the badlands.

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Yellowstone National Park's most famous hot spring, the Grand Prismatic's vivid blue centre is surrounded by bands of rusty orange, yellow and green, making it look otherworldly. A half-mile (800m) boardwalk loops around the hot spring as well as the other pools in the Midway Geyser Basin. However, Grand Prismatic is so large, it'll be hard to make out its shape. After you've seen it up close, head to the nearby Grand Prismatic Spring Overlook for a breathtaking view from further away.

Allow a few hours to zigzag your way up this 50-mile (80km) mountain road in Glacier National Park. As you climb higher and the air becomes thinner, the scenery gets ever more spectacular. Mountain goats cling to cliff sides, glaciers peek above pine forest and flower-strewn valleys tumble down to glassy lakes. Plan stops at Jackson Glacier Overlook, with a perfectly framed view of the park’s seventh-largest glacier, and Logan Pass, the highest spot you can reach by car.

Famed for its beautiful vistas, cliffs and lush forests, Yosemite National Park is full of big-hitter attractions like Half Dome and El Capitan, but there's nothing quite like Yosemite Valley. Head to the Tunnel View viewpoint to see the jaw-dropping landscape in all its splendour. There are several day hikes, from short and easy to seriously strenuous, to explore this area of the park up close.

America’s second national park, Sequoia National Park, was created to protect the towering sequoia trees to which it owes its name from logging. Today, the oldest tree in the 629-square-mile (1,629sq km) Sequoia & Kings Canyon National Park is General Sherman – it’s thought to be 2,300 to 2,700 years old. Foliage aside, the park’s diverse landscape includes a significant portion of the Sierra Nevada mountains, as well as deep canyons, craggy foothills and impressive caverns.

With the highest density of natural arches in the world, Arches National Park in Utah boasts more than 2,000 of these natural red sandstone formations, the most famous being Delicate Arch. The 52-foot (16m) freestanding arch is among the park's most popular attractions and there's a 1.5-mile (2.4km) hiking trail leading up to the famous sight.

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One of the most active volcanoes in the world, Kīlauea is located in Hawai'i Volcanoes National Park that also encompasses the world's biggest shield volcano, Mauna Loa. In addition to the incredible volcanic scenery of black rock and flowing molten lava, the park is also a refuge for some of the rarest flora and fauna in the world. One of the most popular routes to see the top sights within the park, including Kīlauea, is the 11-mile (17.7km) Crater Rim Drive.

Straddling the California-Nevada state border, Zabriskie Point is the perfect place to look over the badlands of Death Valley National Park. The peculiar wave-like pattern of these hills is the result of Furnace Creek Lake, which dried up five million years ago, and erosion. Head here at sunrise or sunset, when the slopes look particularly spectacular.

This 275-square-mile (712sq km) desert in New Mexico's Tularosa Basin is an unusual natural phenomenon. The dunes at White Sands National Park are formed by gypsum sand – a rare mineral found only in a few places on the planet. Since it dissolves in water, it's almost a miracle such large quantities of it exist in one place but thanks to New Mexico's dry climate, the sand thrives here, creating a magical landscape. Explore by hiking one of the many trails.

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Fort Jefferson is a brooding landmark in Dry Tortugas National Park, in the Florida Keys. Nicknamed the Guardian of the Gulf, the fort dates to the 19th century and was used as a prison for Union deserters during the Civil War. It has been defunct since the Second World War and is now a top spot for snorkelling, swimming, camping and fishing (make sure to bring your own saltwater fishing licence for this though).

Rugged Theodore Roosevelt National Park has epic road trip potential and, conditions permitting, its scenic driving routes remain open throughout the year. Drivers can typically take to jaw-dropping slices of the South Unit scenic loop drive and North Unit Scenic Road, drinking in the picturesque badlands and spotting wildlife like elk and bison. However, be sure to check for closures, which aren't uncommon.

One of America's most famous roads, Skyline Drive is a showstopper at any time of year, but visitors are likely to find the route particularly charming in autumn. The three-hour drive offers sweeping views over Shenandoah National Park, whose canopy glows in amber and gold at this time of year, while in spring and summer, the road is hugged by the green wave of the trees. The highway is also studded with a series of overlooks offering panoramas over the stirring foliage. 

Wizard Island – the cinder cone that rises from Crater Lake's glassy surface – is one of the most dramatic sights in this national park. It's a photographer's dream, with imposing peaks surrounding the mirror-like water of the lake. Take on routes like the Scenic Rim Drive for sweeping views of the lake and the caldera from 30 overlooks along the way.

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Often considered one of the prettiest beaches in the country, Ruby Beach is the crown jewel of Olympic National Park in Washington state. Famous for its dramatic scenery of weathered driftwood, sea stacks and the Jurassic Park-esque forest that surrounds it, the beach is named after the ruby-like crystals in the sand. It's an incredibly atmospheric destination perfect for restorative and relaxing walks.

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