Yosemite is open 365 days a year, but May and June are the only months when every area of the park is likely to be accessible. All of the water flowing into the giant reserve, located in eastern California, comes from snowmelt, so early summer also means that the waterfalls will be flowing powerfully. Finally, the park will be covered in wildflowers, since most of that blooming occurs in June. Santini / De Agostini /Getty Images Montana’s Glacier National Park is a destination for 2 million visitors every year. Though it’s open all year, extreme winter weather causes many facilities to close at unpredictable times. Most of them are back on track from May to September, making June a perfect time for a visit. One great hiking option is the Hidden Lake Nature Trail. It's a 1.5-mile self-guided trail that runs to the Hidden Lake overlook, which provides a great view of the majestic water. Along the way, you can observe abundant wildflowers, which are protected by a boardwalk. AP Photo / National Park Service Take a break from the beach and take a hike along the Na Pali coast of Kauai. The trail stretches for 11 miles along scenic, rugged coastlines. The trail offers the only land access to this part of the coast; it crosses above towering sea cliffs and through five valleys before ending at Kalalau Beach. This summer vacation excursion is not for the faint of heart; it takes most backpackers in good condition a full day to traverse. Hutch Axilrod / Getty Images Maroon Bells is a twin-peaked mountain, sitting just above 14,000 feet. They are two of the most photographed peaks in North America. The mountain is located just a few miles from Aspen, Colorado, and tourists head to the area in droves every summer. Buses run frequently, but auto traffic is restricted in summer to cut back on crowds. The surrounding Maroon Valley features 100 miles of trails for hikers of all skill levels. Scenics of America / PhotoLink Zion National Park in Utah offers some of the best hiking the desert can offer, passing beautiful cliffs and canyons along the way. And for those up for additional adventure, the walls of the Zion Narrows offer the best gorge hiking in the United States. Lisa Romerein / Getty Images Officially, the Pacific Crest Trail spans 2,650 miles through three states, seven national parks, passes more than 1,000 lakes along the way, and goes over 60 mountain passes. You may not be looking for an adventure quite that Herculean, though. Luckily, the trail has access points near many major cities, including Los Angeles, San Francisco, and Portland. Paul Souders / Getty Images Any East Coaster feeling jealous of the Pacific Crest Trail should know that the Appalachian Trail stretches almost as far—2,178 miles, and passes through 14 states. Much of the trail passes through deciduous forests, which are beautiful in their own way, but block out the view. So head to the Southern Appalachian Balds section, which stretches south from Troutdale, Virginia, into Tennessee. This section of the trail offers the opportunity to play with grazing ponies and take in the view from Roan Mountain, which, at 6,285 feet, is the highest mountain on the stretch. Getty Images Hawaii Volcanoes National Park is home to two of Hawaii’s active volcanoes. Kilauea, the 4,000-foot high mountain, has been steadily erupting since Jan. 3, 1983, and it is estimated that 500 acres of new land have sprung up since that day. The other volcano, Mount Kilauea, reaches 14,000 feet and is the largest volcano on earth. Hikers hoping to see lava can check in at the Kilauea Visitor Center to find out where to see lava flow. Some visitors trek through the park for days, but those short on time can opt for a three-hour hike and still see the highlights. Brad Lewis / Getty Images Discovery Park covers more than 500 acres in northern Seattle. Features of the park include miles of hiking trails, saltwater beaches, and sand dunes. A hike along the North Beach Trail will take you to the West Point Lighthouse, while a hike along the South Beach Trail will afford you a great view of Mount Rainier and Seattle’s skyline. The best part: Entry is free. Karl Weatherly / Getty Images This rim features popular trails—some good for children and some for more advanced hikers. If you’re willing to combine a hike and a drive, you can travel through the Kaibab National Forest up 8,803 feet to Point Imperial, which provides the highest vista on either side of the gorge. And there’s only one season to do it: Summer is the only time of year that the North Rim is fully accessible; the road from Jacob Lake to the North Rim can be closed because of snow the rest of the year. Paul Edmondson / Getty Images California’s rugged Mount Lee is not just a beautiful slope—it’s also home to the world-famous Hollywood sign. There's a 6.5-mile trail that will take you from Griffith Park right to the back of the iconic letters. (Because of the way the sign is fenced off, this is actually as close as you can get.) Once at the sign, be prepared for great views of the city below and the Pacific Ocean beyond—and you can snap a great shot of the sign from a unique angle. David McNew / Getty Images Banff is probably as close as you can get to a Swiss skiing village without going to Europe—you will have to venture to Canada, however. Skiers will obviously want to visit in winter, though in January, the average high is 23 degrees Fahrenheit. However, nature lovers should visit Banff and its national park in June and August, when the temperatures are milder. Past visitors recommend hiking around Moraine Lake, which is so beautiful that it is actually featured on the Canadian $20 bill. Getty Images