Hike past Eagle Falls (about 1 mi from the parking lot) to Eagle Lake, where you can shed your clothes (bring a suit weekends) and dive into cold, blue, alpine water.
There are dramatic views from the pool deck at the High Camp Bath and Tennis Club (530/581-7255. www.squaw.com), where you can swim laps or soak in the 25-person hot tub for $26, which includes the cable-car ride; for $3 more you can ice-skate, too. Prices drop after 5.