America's national parks are brimming with natural wonders: cascading waterfalls, towering redwoods, white sand beaches. But visiting these gems can cost money and soon will get a little pricier: Many national parks will increase their entrance fees by $5 beginning June 1. In honor of National Park Week April 21-29, here are seven ways to plan a cheaper national park trip. 1. TRAVEL OFF-PEAK Mikah Meyer, 32, wants to become the youngest person to visit all 417 National Park Service sites. In the past two years, the Nebraska native has crossed more than 300 off the list while living out of his trusty 2014 Ram ProMaster, a white, windowless cargo van he's dubbed "Vanny McVanface." He's just one of the more than 330 million people who visited the national park system in 2017. Rooms and campsites fill up fast during weekends, spring break and summer. Meyer suggests visiting offseason to save money and avoid crowds. But there are trade-offs. "Sometimes you'll go to parks like Yosemite where certain trails and waterfalls are closed because they're snowed in," Meyer says. Research seasonal conditions to prevent surprises, and note that some destinations have atypical high seasons. Warm-weather parks such as Death Valley and Everglades are busiest in winter. 2. VISIT FOR FREE More than two-thirds of national parks are free year-round. The others waive entrance fees on certain dates. The remaining fee-free days in 2018 are: —First day of National Park Week: April 21 —National Public Lands Day: Sept. 22 —Veterans Day: Nov. 11 With free days dwindling — down from 10 in 2017 to four in 2018 — and potential fee hikes looming, take advantage. 3. ANNUAL PASSES AND DISCOUNTS An annual pass costs $80 and can pay for itself if you plan to visit multiple parks in a 12-month period. U.S. military members can get the annual pass for free, as can fourth-grade students and certain volunteers. For seniors, annual passes cost $20 and lifetime passes $80. Lifetime passes are free for those with permanent disabilities. Travelers can also leverage perks offered by wholesale clubs, frequent flyer programs and other memberships, such as AAA. 4. SKIP THE EXPENSIVE LODGE Camp by tent or vehicle to cut costs. Backcountry campsites, which are generally in remote areas accessible only on foot, are usually cheaper than developed campsites, says Kathy Kupper, public affairs specialist for the National Park Service. Campsites at Glacier National Park cost a maximum of $23 per night during peak season, for example, compared with the hundreds of dollars a night you might pay to stay in a lodge. To avoid camping fees outright, Meyer parks in Walmart or hotel parking lots that allow it. He also camps free in U.S. Forest Service and Bureau of Land Management areas near national parks. "Sometimes they have actual campsites with running water and bathrooms, and other times it's just wherever you can fit your car, there you go," Meyer says. Contact your local agency offices for details. If roughing it doesn't appeal to you, try hotels or rentals in gateway communities. Neighboring towns typically have more rooms and are less expensive than park lodges. 5. BUY SUPPLIES BEFOREHAND Don't wait until you're near or inside the park to stock up on food, gas and other essentials. "The closer you get to these places, especially when they're out in the wilderness, there's going to be that convenience charge," Meyer says. "Something you might buy for $3 at your local grocery store could be $7 or $8 in the middle of nowhere." 6. EXPLORE YOUR BACKYARD Every state has at least one national park site, so you don't necessarily have to spend a lot of money to travel to one. "It's not always saving up for that once-in-a-lifetime trip to the Grand Canyon. You can go for a day or a weekend to a park near you," Kupper says. 7. LOOK FOR FREE ACTIVITIES National Park Service programming, with very few exceptions, is free, Kupper says. That includes activities like ranger-led hikes, snowshoe walks and kayak tours. You can see potential itineraries and book tours at the National Park Service website. Once in the park, stop by a visitor center for more information. "Spending time in nature is good for body and soul," Kupper says. Doing it cheaply can be good for your wallet, too. This article was provided to The Associated Press by the personal finance website NerdWallet. Lauren Schwahn is a writer at NerdWallet. Email: lschwahn@nerdwallet.com. Twitter: @lauren_schwahn. RELATED LINKS: NerdWallet: How to save money https://nerd.me/how -to-save-money National Park Service https://www.nps.gov/planyourvisit/trip -ideas.htm