In The Best Things in Life are Free: The Ultimate Money-Saving Travel Guide, the travel experts at Lonely Planet collected the most priceless experiences they've discovered from over 40 years of on-the-ground research into one essential resource. Packed with money-saving tips, tricks and recommendations, The Best Things in Life are Free features 884 free (or almost free) sights and experiences in 60 major cities around the world from Boston to Bangkok.

Looking for a free yoga class in Dubai, or an outdoor concert in San Francisco? How about a movie night in New Orleans, or an open-air market in Marrakesh? From public parks, museums, and free exercise classes to the best sunset spots, cheap food, and other affordable experiences,The Best Things in Life are Free is the key to experiencing more of the world without breaking the bank.

Here are Lonely Planet’s Top 10 Free-Range Adventures in America’s National Parks, excerpted from the book.

North America vertical hiking

The 1.8 mile-/3.2km-long Precipice Trail dramatically ascends the east face of Champlain Mountain, along super-narrow ledges with vertical climbs up via ferrata-style rungs. nps.gov/acad; Mount Desert Island, Acadia National Park; opening hours vary; $15 individual 7-day pass.

Challenge your fear of heights in Acadia National Park. © Ken Brown / Getty Images

Wild hot-tubbing

Park on the 45th parallel and follow the steam to Boiling River, a bathing spot where hot springs enter Gardner River to create perfect soaking conditions. www.nps.gov/yell; Mammoth Hot Springs, Yellowstone National Park, ID, MT + WY; 24hr; $15 individual 7-day pass.

People soaking in Boiling River, Yellowstone National Park. © Matt Munro / Lonely Planet

Flower power

More than 1500 wildflowers explode into colour beneath the Appalachians during spring. Go backcountry hiking and wild camping ($14 to $23 per night) amid the blooming ephemerals. Watch out for black bears. nps.gov/grsm; Great Smoky Mountains National Park, NC + TN; 24hr; free.

Watch your step as you gaze at the wild flowers blooming in the Smoky Mountains. © Betty4240 / Getty Images

Snorkel around a fort

Seventy miles (110km) from Key West, perched on a coral atoll, Fort Jefferson is the scene of much marine activity. Snorkel around the moat and sea wall, amid fish, coral and wrecks. nps.gov/drto; Dry Tortugas National Park, FL; 24hr; $5 7-day pass.

Fort Jefferson in Dry Tortugas National Park. © Mark Read / Lonely Planet

Waterfall walking

The best short hike in an epic Sierra Nevada nirvana, this 6.5 mile/10.4km-long trail passes through the thundering mist created by two magnificent cascades: Vernal Falls and Nevada Falls. nps.gov/yose; Mist Trail, Yosemite National Park, CA; 24hr; $15 individual 7-day pass.

Water pouring over Vernal Falls, Yosemite National Park. © Mark Read / Lonely Planet. From Lonely Planet's Top 10 Free-Range Adventures in America’s National Parks    

Go bear

Few encounters are as exciting as running into a big brown bear. Fortunately, at Brooks Camp, the bears have tastier fish to fry than you. July-September is the best time to see them. nps.gov/katm; 24hr; Brooks Camp, Katmai National Park, AL; free.

Coastal brown bears relax and play near a creek in Katmai National Park and Preserve, Alaska. © Chase Dekker Wild-Life Images / Getty Images

Moon-walking

Two hours’ drive from the neon glow of Vegas, the night sky is so clear you can regularly see five planets. Rangers offer free lunar-lit night hikes in summer when there’s a full moon. nps.gov/grba; Great Basin National Park, NV; 24hr; free.

Head to Great Basin National Park for some top-notch star gazing. © Gromit702 / Getty Images

Volcano voyeurism

Surf’s up in Hawai’i, and so is the lava… Kīlauea volcano remains active, and the spitting vent in Halema’uma’u crater can be viewed from the overlook at Jaggar Museum. nps.gov/havo; Hawai’i Volcanoes National Park, HI; 24hr; $8 individual 7-day pass.

Halema'u ma'u Crater under stars of Milky Way in Volcanoes National Park. © Matt Munro / Lonely Planet

Hunt bison

Follow in the footsteps of the Conservationist President in the park named in his honour, by exploring the badland prairies and fixing a mighty bison in your camera’s crosshairs. nps.gov/thro; Theodore Roosevelt National Park, ND; 24hr; $10 individual 7-day pass.

Theodore Roosevelt National Park, North Dakota. © Comstock Images / Getty Images

Travel through space and time

A dark-sky park, Chaco has terrestrial wonders to complement its heavenly delights, with 1000-year-old Puebloan ruins, built to align with the stars during the equinox. Rangers offer free tours. nps.gov/chcu; Chaco Culture National Historical Park, NM; 7am-sunset; $6 individual 7-day pass.

Chaco Culture National Monument. © Justin Foulkes / Lonely Planet

Read more:
www.lonelyplanet.com/free

And our National Parks: Nps.Gov

Reproduced with permission from The Best Things in Life are Free, © 2016 Lonely Planet