Nature's swimming pools are key to beating the summer heat. Fortunately, you'll find them everywhere, from New York to California.

(Sona Shah | Travel Leisure)

Standing in the sunshine on the rocky bank, with rivulets of cool water dripping from your hair and swimsuit, you wait your turn at the base of the old oak. You're up. You grip the fraying rope, get a running start, swing out over the pool of clear water, and release. Cannonball!

In summertime, when the mercury taunts the tip of the thermometer like an angry red fist, the best place to cool down is an old-fashioned swimming hole. These often-secluded natural pools are the perfect antidote to crowded pools with zinc-covered teenage lifeguards or water parks with $8 hot dogs. And they offer a dose of not-yet-forgotten Americana, where sunny days are measured by best friends and belly flops.

Searching for the best swimming spots

Pancho Doll, a former writer for the Los Angeles Times, is something of an aficionado. For his first book, Day Trips with a Splash: Swimming Holes of California, Doll logged 25,000 miles in his truck searching the state for the best, from the Oregon state line to San Diego County. He has since penned a whole series that chronicles the best freshwater spots across the country. This is a man who knows a thing or two about taking a dip. "The Holy Trinity of swimming-hole quality is height, depth, and privacy," says Doll. "Surrounding rock provides a sense of enclosure, often a nice slab inclined for summer repose, even a ledge to jump from."

And what says "swimming hole" more than an old-fashioned rope swing? At the cypress-studded Blue Hole in Wimberley, Texas, three such swings hang from burly tree limbs. Drop in with the Austinites who come to float on inner tubes and picnic on the grassy banks.

While these natural oases might seem most at home in the South, you'll find swimming holes across the country. At Peekamoose Blue Hole in New York State's Catskill Mountains, dappled light bounces off leafy canopies and swimmers submerge themselves in the cool waters like an invigorating summer baptism.

So grab your swimsuit, a towel, and a pair of water shoes, and jump in at some of our favorite swimming holes. Last one in's a rotten egg!

Little River Canyon

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Fort Payne, Alabama

In northeastern Alabama, the Little River snakes across the top of Lookout Mountain before plummeting into the 12-mile-long Little River Canyon.Bordered by broad-faced cliffs, with large blocks of sandstone jutting from the water, this canyon — at 600 feet, the deepest this side of the Mississippi — is home to a handful of perfect swimming holes.

Just downstream from the Alabama Highway 35 bridge, follow the short paved path to the bottom of Little River Falls for an easy-access dunk when water levels are low. (High water means dangerous currents.)

Or start at Eberhart Point and hike 0.75 miles to the canyon floor to Hippy Hole, where rope swings dangle from trees and a series of cliffs serve as springboards for daredevils.

Havasu Falls

(Sona Shah | Travel Leisure)

Supai, Arizona

There's off the beaten path. And then there's Havasu Falls — located a mile and a half outside the Havasupai Indian village of Supai, on the bottom of the Grand Canyon. The only way to get here is to charter a helicopter, hike a steep 10 miles, or hire a pack animal. (The U.S. Post Office still uses mules to make mail deliveries to the village.) And you'll need a permit ($20). But boy, is it worth it. A torrent of water streams across the sunburnt rock face of the Grand Canyon's south rim, collecting in a pool 100 feet below.

The water, so turquoise it looks like it's on loan from the Caribbean, stays about 72 degrees year-round and is perfect for lazy floating or practicing your belly flop. And with such a schlep to get here, you don't have to fight the crowds for a prime sunning spot. Yeah, it's pretty much the best swimming hole ever.

Carlon Falls

(Susanna Coffin | Travel Leisure)

Yosemite National Park, California

En route to Hetch Hetchy, pull off winding Evergreen Road at the South Fork Tuolumne River for a mostly flat, two-mile hike to this rare year-round waterfall. Bordered by towering ponderosa pines, with meadows of purple lupine and small bright sunflowers nearby, this secret swimming hole is rarely visited by Yosemite pilgrims.

The 35-foot falls cascades over wide granite ledges into a boulder-strewn pool, where, most of the time, the birds in the canopy and the whoosh of rushing water are the only other sounds you'll hear. Exactly how a good swimming hole should be.

Redfish Lake

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Stanley, Idaho

In an area where salmon outnumber people, Redfish Lake, outside Stanley (population: 106), is a jaw-dropping example of why you explore the backcountry. Legend has it, there were once so many sockeye salmon spawning in the lake that it appeared red. Hence the name. Now it's better known for its vast bird population, including peregrine falcons and songbirds like yellow-flecked Townsend's warblers and ruby-crowned kinglets.

Laze on the south-shore beach for staggering views of the snowcapped Sawtooth Range reflected in the pristine waters. Once you've been here, the words "untouched wilderness" will have a whole new meaning.

Echo Lake

(Sona Shah | Travel Leisure)

Mount Desert Island, Maine

On Mount Desert Island, fingerlike fjords carved by glaciers define the rugged salt-licked coastline. But in the southwestern interior, the beach at Echo Lake (about 20 minutes from Bar Harbor) slopes gently into deep blue fresh water.At its deepest, the placid lake is only 66 feet. And while it's warmer than the shockingly cold northern Atlantic, temperatures rarely get above 55 degrees.

We recommend working up a sweat on the Beech Mountain hiking trails, with bluffs and overlooks that perfectly frame the lake's crescent-shaped gravel beach, before taking the polar bear plunge. Then hop back into town on the free Island Explorer Shuttle Bus, which makes hourly runs between the lake and the village green.