Martha's Falls, also called Little Falls and known to locals as the "Hippie Hole," is the most beloved swimming hole in the Little River Canyon National Preserve near Fort Payne, Alabama, and one of the most photographed spots in the state. It is not a tall waterfall but a wide one: the Little River slides over a broad, low shelf of sandstone into a generous pool whose water glows an almost unreal emerald green. That color is the tell of a sky-fed river running clear over pale stone, and the pool has been carved into the canyon floor over thousands of years, deep enough in the middle for real swimming and shallow at the edges for kids and waders.

The low ledge is made for sliding and small jumps, and the rock walls around the pool give bolder swimmers a range of higher launch points, though how high is safe changes with the water level. On a hot Alabama afternoon it fills with families, teenagers and out-of-towners; international "best swimming holes" lists have found it in recent years, and summer weekends can be genuinely busy, so an early start or a weekday visit buys you more of the canyon to yourself.

Reaching the water is the price of admission. Parking is a lot off Highway 35 near County Road 861, and the trail down is close to a mile. It begins gently, an easy five-minute walk along a gravel service road, then turns left onto a rooted footpath and drops steeply over the last hundred yards of rocky ground to the canyon floor. The park has added stone steps on the steepest section, which helps, but the trail is still rated moderate-to-strenuous and can be slick when wet, and the climb back out in the heat is the hard part.

Facilities are deliberately minimal: there are no picnic tables and no trash service down at the water, dogs are welcome on a six-foot leash, and alcohol is not permitted anywhere in the preserve. The biggest thing to respect is the river itself. Levels and current rise fast after rain, the smooth rock gets slippery, and what looks like a calm pool can develop real pull, so it pays to look before you leap and to check conditions after a storm.

Late spring through early fall is the swimming season, midsummer the warmest and most crowded, the shoulder weeks quieter and cooler. Martha's Falls sits partway down the gorge from Little River Falls at the head of the canyon, so it pairs naturally with a stop at the falls overlook and a drive along the 22-mile Little River Canyon Rim Parkway. For clear green water in a rugged sandstone canyon, earned by a short, sweaty hike, it is hard to beat in the Southeast.