The third highest peak in the Oregon Cascades actually has one route that can be climbed with little technical skill or equipment during the summer months. The south side route from either Green Lakes or Devils Lake requires mainly good physical conditioning to attain the broad summit cone at 10,358 feet.

Other routes offer more technical challenges and diverse climbing scenery. The east side routes include Prouty Glacier and the Prouty Headwall, and from the north approaching from Middle Sister energetic climbers can take the North Ridge, Silver Couloir, and the North Face Couloir which is a demanding remote north side cirque that offers multiple pitches of snow or ice climbing

In addition to climbing, camping and hiking opportunities abound around South Sister. Green Lakes and Morain Lake lie to the east, the Pacific Crest Trail runs just west of the mountain, and Camp Lake and Chambers Lakes are like blue-green jewels in the high alpine moraine plateau which lies between South and Middle Sisters' eastern slopes.