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Havasu Falls, Supai, Arizona
This shocking Caribbean-blue pool—on the bottom of the Grand Canyon near the Native American community of Supai—is for the most tenacious of swimming-hole devotees. There are only three ways to get to Havasu Falls: hire a helicopter, hike 10 miles, or ride a pack mule. Plus, you'll need to purchase an entry permit, and, unless you're a hardcore trail runner, book a night at the Havasupai Lodge or campsite. But it's so worth it. Pancho Doll, who wrote two books on America's swimming holes, calls it the best in the world. After a long desert trek, even the mist from the 120-foot cascade is refreshing. Swimming behind the torrential falls or floating on your back and taking in the view is the real reward.
What's Nearby: Supai has a small grocery store and cafe. It's also one of two places in the country where U.S. mail is delivered by mules.