From postcard beaches to steaming volcanoes, sunburned canyons to snow-capped mountains, the United States just about has it all. The National Parks Service was created in 1916 by an act signed by President Woodrow Wilson, originally to protect the land that we now know as Yellowstone National Park. Now, a century later, the United States has 59 national parks, each protecting and highlighting the ecological diversity of America.

The National Parks centennial brought in a record-setting 330,971,689 recreation visits in 2016, and that number was almost matched the following year. The top five most visited parks in 2017 were the Great Smoky Mountains, Grand Canyon, Zion, Rocky Mountains, and, of course, Yosemite, according to Outdoor Society.

From the hot, sandy canyons of Utah to Alaska's icy peaks, each and every one of the parks is unique and worth visiting, but some are inevitably grander than others. If you're wondering which ones to visit now and which ones to save for later, here are 10 to see now and 10 to hold off on.

20 Visit Now: Glacier National Park, Montana

More than 1 million acres of picture-perfect mountains and lakes that make up Glacier National Park were all formed by — you guessed it — glaciers. The park remains one of the biggest ecosystems in the temperate zone, even spilling over into the British Columbia and Alberta regions of Canada. This multi-national nature sanctuary is visited by more than 3 million people per year, according to Lonely Planet, which makes it the tenth most visited national park in the United States. There's no wonder why so many flock to this Montana oasis because there's plenty to do for every age, interest and fitness level, from boating to backcountry skiing. There are more than 700 lakes to swim in and 151 trails to trek. Glacier National Park is worth the visit even if you choose not to get out of the car. The Going-to-the-Sun Road that runs through the park, which has been named a National Historic Landmark, is one of the most scenic drives in North America.

19 Visit Now: Yosemite National Park, California

If the states had personalities of their own, California would be the one who always competes to be the biggest and the best, and its crown jewel national park aptly follows suit. Yosemite National Park is home to the highest waterfall in North America (Yosemite Falls) and the tallest granite monolith in the entire world (El Capitan). Avid rock climbers come from all over the country (and the world) to climb the valley's soaring granite peaks. But even if hanging off the side of a granite wall or hiking up the 5,000-foot-tall Half Dome aren't your forte, there's still plenty to see (such as climbers through permanent, park-provided telescopes) and photograph from the valley floor. Popular activities include rafting down the Merced River, biking around the 12 miles of paved path and endless mountain biking opportunities off-trail, and camping in the pristine John Muir wilderness.

18 Visit Now: Bryce Canyon National Park, Utah

On the eastern edge of south central Utah's Paunsaugunt Plateau, Bryce Canyon promises "orange hoodoos and stunning vistas" that are sure to blow you away. These peculiar rock pillars (hoodoos) that give Bryce Canyon its otherworldly aesthetic were caused by forces of erosion, according to the National Parks Service, creating what they call a "forest of stone." This colorful desert oasis sits so far from city lights that it offers supreme dark skies at night, ideal for stargazing, and holds an annual Astronomy Festival in June. Hikers are treated to panoramic views of the vast canyonland on the park's Rim Trail, while horseback and ATV tours will give you a more exclusive experience.

17 Visit Now: Joshua Tree National Park, California

The stargazing isn't too shabby here, either, but what Joshua Tree is really known for is its fiery red sunsets. Magic hours in this national park are best spent at the Keys View lookout point, in the Little San Bernardino Mountains, overlooking the Salton Sea, Coachella Valley and the San Andreas Fault, the Evening Standard says. Sunrise, on the other hand, looks best from the ground, where you can watch the Cholla Cactus Garden glow gold. Besides the distinctive yucca plants after which the park is named, "J-Tree," as it's been nicknamed, is also known for its towering boulder formations, offering world-class climbing during the cooler months. Many come to hike, climb, view wildflowers, and camp, but a cruise along the backcountry roads of California, where the high Mohave meets the low Colorado desert, is just as fun.

16 Visit Now: Denali National Park, Alaska

Alaska is home to seven of the 10 largest national parks in the country, with the biggest (Wrangell-St. Elias National Park) spanning over more than 8 million acres. The third largest, spreading over almost five million acres, is also home to the highest mountain in North America. Standing 20,310 feet tall, Denali's snow-capped peak is the centerpiece of this national park. Scaling Mt. McKinley, as it's also called, requires advanced mountaineering skills, but nature-lovers won't be disappointed in simply marveling at its rugged ridges and watching the resident bears, bighorn sheep, moose, elk, and caribou roam about from below.

15 Visit Now: Yellowstone National Park, Wyoming/Montana

Any roundup of America's best national parks would be incomplete without a mention of its oldest. Established by congress on March 1, 1872, 146-year-old Yellowstone National Park was the first national park in the United States and, according to Encyclopedia Britannica, potentially the first in the world. It's certainly one of the most unique, too, with hot springs so vibrantly colorful they look like they're from another planet, and a geyser that, once per hour, shoots water 100 feet into the sky. In fact, half of the geothermal features in the world are located in Yellowstone, according to Modern Day Explorer, with near-molten rock flowing just a few miles below the surface of some.

14 Visit Now: Hawai'i Volcanoes National Park, Hawai'i

Speaking of molten rock, the volcanoes of Hawai'i's Big Island are a must-see for national parks enthusiasts. The famous 10.6-mile Crater Rim Drive scenic loop in Hawai'i Volcanoes National Park takes visitors on a wild ride through thick tree fern forests and steam vents, weaving between smoking lava fields. The 11-mile Crater Rim Trail leads visitors right through an active volcano (safely, of course) and around the summit caldera of one of the park's most famous volcanoes, Kilauea. The national park's website lets you monitor lava flow so you can actually walk out to see it sliding down the slopes of Kilauea into the Pacific Ocean — now, that's a sight you wouldn't be able to see just any old day.

13 Visit Now: Grand Canyon National Park, Arizona

The United States is home to one of the Seven Natural Wonders of the World. The 277-mile-long Grand Canyon is a mile deep and 18 miles wide in places. This vast landscape was astoundingly carved out more than 17 million years ago by the Colorado River, a true testament to the power of nature. The spirituality is palpable in this holy land, still worshipped by the Native American tribes who live on the canyon floor today, and whose rich culture radiates throughout the park. The South Rim portion of the park offers easy-to-difficult hiking trails on top and into the canyon, train tours, and ample viewing platforms overlooking the valley. The North Rim caters less to tourism but offers more opportunities to get off the beaten path, away from the masses, and be one with this historic, sacred place.

12 Visit Now: Zion National Park, Utah

This red rock paradise in Utah was the third most visited US national park in 2017, behind the Great Smoky Mountains and Yosemite, according to the LA Times. Maybe this is because the park is home to some of the most adventurous day hikes in America — including the steep and exposed cliffside hike Angel's Landing and a hike through waist-deep water in The Narrows — or because its narrow slot canyons make for good Instagram posts, or perhaps because the location of the park makes it accessible to the entire West Coast. Whatever the reason, the number of visitors to Zion has increased by 60 percent over the past five years.

11 Visit Now: Sequoia National Park, California

About 100 air-miles south of Yosemite is another one of America's favorite national parks. Standing beneath the towering canopy of the Giant Forest in Sequoia National Park would make even the tallest man feel tiny. In 2017, a record 1.2 million people came to hug the trees' ancient trunks, camp amidst their prickly leaves, and walk atop their roots. The park is home to the 3,000-year-old General Sherman — the largest living thing on earth, towering 275 feet high and 36 feet wide — clusters of colossal trees dubbed "The House" and "The Senate," and the iconic Tunnel Log, a fallen-over tree that has been cut over the road for tourists to drive through.

10 Visit Later: Congaree National Park, South Carolina

This hardwood forest is South Carolina's only national park. If you're in the area, it's worth a visit for a day hike or a cruise by kayak on the Congaree and Wateree Rivers alongside the resident otters. If you're not in the area, however, you might just want to wait until you're passing through to visit Congaree. Why, you ask? For one, the park mostly only caters to short-term visitors. Unlike bigger parks, you won't find any lodges here; only backcountry camping. And don't get us wrong: this land deserves to be protected because it boasts some of the last swampland left in the state; however, with swampland comes a lot of unlovable things, such as thick humidity, ferocious mosquitos and venomous snakes — three species of them, in fact.

9 Visit Later: Wind Cave, South Dakota

South Dakota is a haven for nature lovers, with vast prairie and pine forests where the buffalo roam and the deer and antelope play, much like the old song goes. However, if you are one who has seen a few epic caves in your day, you might find the Wind Cave underwhelming. Travel blogger Lee Abbamonte did, at least, saying that the more than 300 stairs that take you down into the cave are treacherous when wet and, once inside, there weren't any stalagmites or stalactites to study; only "cave popcorn" and thin ceiling rocks.

8 Visit Later: Voyageurs National Park, Minnesota

This water-based park on the border of Canada is best — or, shall we say, only— explored by boat. Island hopping on Rainy, Kabetogama, and Namakan Lakes would make for a fun day, unless, of course, you get easily waterlogged. With 655 miles of shoreline and more than 500 islands, according to USA Today, exploring the park entails lots of time on the water, and doesn't offer a whole lot of on-land options save a few hiking trails and visitors centers. Needless to say, this is a lake-lovers-only kind of spot, so if boat tours and sleeping on house boats isn't really your thing, then maybe you should skip Voyageurs for now and find something else on land.

7 Visit Later: Dry Tortugas National Park, Florida

A visit to Dry Tortugas is a big commitment. Located in the Florida Keys, the islands that make up this national park are so remote they require visitors to travel by seaplane or boat. The park spans over 100 square miles, but less than 1 percent of it is above water, so this park entails lots of time at sea. The coral reefs here are buzzing with marine life, which make for great snorkeling and scuba diving. However, and once you get waterlogged, there's hardly anything else to keep you entertained, so plan wisely.

6 Visit Later: Death Valley National Park, California

The spectacular sand dune scenery of Death Valley National Park is as photogenic as the desert gets, and there's no question that the 3.4-million-acre park (the largest in the contiguous United States, according to the National Parks Service) is an ecological treasure that is worthy of preservation; however, visiting the park isn't easy for an average Joe. For starters, the dry and really — really — hot climate (sometimes exceeding 120ºF in the summer) is not the most comfortable or healthy environment in which to be exploring the outdoors. Wintertime is really the only bearable season to visit this California park, but even then — if you can believe it — it's often uncomfortably cold!

5 Visit Later: Hot Springs National Park, Arkansas

This 5,550-acre space is the smallest national park in the United States. The water in these hot springs is so clean you can drink it — and people do! Historically, Native Americans used to worship these pools for their healing properties, and today, visitors can dip into the holy waters without paying a cent. However, while soaking in hot springs is rather relaxing, some people find the park underwhelming. Nobody is as unimpressed by Arkansas' Hot Springs as one Yelp reviewer who described it as "the bargain basement" of national parks, a 2016 Mental Floss article says.

4 Visit Later: Cuyahoga Valley National Park, Ohio

Cuyahoga Valley, just a 20-mile drive from the Midwestern metropolis of Cleveland, is Ohio's only national park. The park is a refuge for native plants and wildlife, surrounding the scenic Cuyahoga River. It's perfect for a Sunday stroll for the locals but perhaps not worth a big trip. The rural landscape is full of lush foliage, which is particularly colorful when the leaves change during autumn, but the scenery here looks a bit like every other countryside. You could arguably catch a glimpse of the same scenery simply driving through Midwestern farmland.

3 Visit Later: Gates Of The Arctic National Park, Alaska

The National Parks Service has dedicated a whole page just to "bugs" in Alaska's Gates Of The Arctic National Park. Visitors should not come to this park unprepared for the relentless swarms of mosquitos, the website says, and should wear extensive protection such as head nets, bug coats, and "assorted insect repellants." The abundance of insects isn't the only thing that deters people from the Gates Of The Arctic, though. This park is the second largest park in the United States. Covering almost 8.5 million acres, this park is an ideal destination for experienced wilderness buffs, but not really for the general public. The park has no roads and the only trails here have been developed by the resident caribou. While the Gates Of The Arctic offers unmatched scenery, it's only accessible to a few.

2 Visit Later: Katmai National Park, Alaska

The one thing that has made Alaska's Katmai National Park famous is what drives people into the park, and also what drives them away: bears. Bears everywhere. About 2,200 of them, according to a 2015 New York Times article. There are so many bears roaming here that the only campground in the park, Brooks Camp, is enclosed by an electric fence, the article says. Upon entering the park, guests are directed to the visitors' center to watch a film about bear etiquette. With this many bears, the campground is strict about its 60-people-per-night limit so as to maintain control if a bear intrudes, which, often, they do. This 60-person-limit also makes booking a spot at Brooks Camp a nightmare. The demand for bear watching is apparently too high for the supply of campsites in Katmai, so sites fill up almost immediately.

1 Visit Later: Great Basin National Park, Nevada

There are plenty of reasons to love Great Basin National Park: it's quiet, secluded, and far away from the civilized world, as one would expect of a patch of pristine wilderness. Whereas the roads in Yosemite Valley are lined on both sides with parked cars and packed with shuttle busses full to the brim with tourists during summer, the road to Great Basin has been dubbed the "loneliest road in America." The park is so remote that it takes more than an hour to drive to the nearest supermarket or hospital. With less than 200,000 annual visitors, it's one of the least visited national parks in the country. Great Basin is where people go to be alone with nature, so if you're prone to loneliness, head down the road to Utah's Zion National Park instead.