When mountain temperatures peak, just add water.
Best For Sunning on the Rocks
Bolton Potholes, Bolton, Vt.
With countless smooth slabs of stone on which to splay your towel and slather up, the Potholes gives sufficient cause to stay out of the water. But when it gets steamy-and it does, even in the Green Mountains-cool down beneath the three waterfalls or natural pools. 877-686-5253
Best For Cliff Jumping
Mushroom Hole, Nevada City, Calif.
The lip of the mushroom-shaped escarpment for which this spot is named is a gutsy 45 feet, blowing the Olympic platform dive out of the proverbial water (it's a measly 33 feet). Aspiring Fear Factor-contestants: Climb the rocks to the ledge, and hold your nose on the l-o-n-g way down. 530-265-4531
Best For Floating in a Tube
Rifle Gap State Park, Rifle, Colo.
At 359 acres, Rifle Gap is a swimming hole on steroids. It's 6,000 feet up in the Rockies on the north slope of the Grand Hogback formation, where the clear, calm mountain waters invite inner-tubers of all ages. 970-625-1607
Best For Having the Place to Yourself
Blue Ledges, Adirondack State Park, N.Y.
At the base of the Hudson River Gorge, Blue Ledges has wide sand beaches and cool, brisk wading waters. The gorge's walls rise in cracks and crevices for 200 feet, so even if you have company, you can still find a spot all to yourself. 518-582-2000