With its Chigmit Mountain peaks, two active volcanoes, alpine tundra, and turquoise lakes so smooth they double as mirrors, Lake Clark National Park and Preserve really is the Last Frontier. The park is only accessible by small aircraft or boat, and it offers magnificent wildlife sightings. The 4,030,005-acre (1,631,000-hectare) park also allows catch-and-release fishing, with species of salmon—including chum, king, coho, pink, and sockeye—spawning in all rivers between June and September.

Straddling the Mexico–US border and with some 500 million years of history, this remote park is one-of-a-kind. Big Bend National Park, which gets its moniker from the dramatic change in direction of the Rio Grand River, is an open-air museum: Estimates say that there are nearly 26,000 archaeological sites spread throughout the park. There are also 200 miles (321 kilometers) of hiking trails and come nightfall, you can gaze up at the night sky and witness 2,000 stars twinkling bright.

When Spanish explorer Ponce de Leon discovered these islets, he christened them Las Tortugas, which translates to “The Turtles,” because of their noticeable presence within the area. Fast forward to today: The region is a scuba diver’s playground with cerulean waters, shipwrecks, and nearly 30 varieties of coral. There are daily boat tours to Dry Tortugas National Park from Key West that typically include a visit to Fort Jefferson and a few hours for swimming and snorkeling.

Created after a prehistoric volcano erupted and collapsed 7,700 years ago, Crater Lake is the deepest lake in the US. Crater Lake National Park becomes a flurry of activity each summer, with daily boat tours of the lake. Back on land, cyclists can spin their wheels around the rigorous 33-mile (53-kilometer) Rim Drive and hikers can give their soles a run for their money on the 90 miles (145 kilometers) of trails.

Poking out of Lake Superior near the Canadian border, Isle Royale National Park is at least 14 miles (22.5 kilometers) from the mainland at its closest point and only accessible via seaplane or boat. Its ecosystem landed it on the country’s International Biosphere Reserve list in 1980, so expect to see species such as moose, gray wolf, snowshoe hare, and more than eight varieties of bats. In addition to great hiking, you can also rent kayaks, canoes, and motorboats at Windigo and Rock Harbor.

Dubbed the Galapagos of North America, this unique archipelago has evolved into its own microcosm. Channel Islands National Park extends to five of the eight islands (Santa Cruz, Santa Barbara, Santa Rosa, San Miguel, and Anacapa) and contains 145 plant and animal species found nowhere else on Earth. Expect to see animals such as the night lizard, island gopher snake, island deer mouse, or island fox; have a field day identifying the almost 800 flora; or dive below the water to find sea caves.

Stretching to the northern limits of Washington State, North Cascades National Park answers your call of the wild with its grizzly and black bears, lynx, mountain goats, wolverines, and 300-plus glaciers. Zealous climbers can obtain a backcountry permit and climb its glacial masses. Many veer off of North Cascades Scenic Highway (Route 20), which has more than 15 notable trails. Don't leave without cruising Lake Chelan up to Stehekin to see the 312-foot (95-meter) Rainbow Falls and Agnes Gorge.

We know the Grand Canyon is perhaps the most famous national park in the world. But it has more than a few secrets tucked within its immense expanse. Our favorite? Havasu Falls. There are no roads in, so your only route is on foot, or via horseback, or helicopter. We suggest taking the slow route, hiking 10 miles (16 kilometers) in to reach waterfalls and pools of brilliant turquoise water amid the warm glow of the orange- and red-hued rocks walls.

After an age-old lake dried up on the San Luis Valley floor, southwesterly winds pushed sand toward the Sangre de Cristo Mountains, with winds from divergent directions shaping the sediment into the dunes you see today. Great Sand Dunes National Park features the tallest dunes in North America and offers visitors the chance to sandboard or sled down mounds of sand as high as 750 feet (229 meters). The park is especially kid-friendly, with junior ranger programs, but also has great hiking.

Redwoods dotted California’s northern coast as long as 20 million years ago, but by the 1960s, the logging industry decimated nearly 90 percent of the population. In a valiant effort to preserve the world’s tallest trees, the Redwood National Park was created in 1968. The best way to comprehend the sheer scale of these giants is by foot, and hiking opportunities abound here. Some great hikes are the James Irvine Trail as well as Miner's Ridge Trail.