There’s something magical about entering a national park: The knowledge that just beyond the gates, some of nature’s most awe-inspiring offerings lay waiting to be explored, from 300,000-year-old volcanoes churning out red-hot lava to spectacularly carved sandstone arches to marshes teeming with wildlife like alligators and manatees. No surprise, then, that the U.S. National Parks draw more than 280 million visitors each year. While the crowds can be overwhelming in the summer, don’t let that stop you from making a visit – with some advance strategies, you can still enjoy solitude. Plus, National Park Week runs through Sunday, with free admission to many national parks. No matter when you visit, though, these national treasures are sure to delight.