The most technically difficult of the three Chicago Basin fourteeners, with a true summit block that requires an exposed Class 4 move to actually touch the high point.
Access is via the Durango & Silverton Narrow Gauge Railroad to Needleton (advance ticket required), then a roughly 6-mile, 2,800–2,900-foot backpack up the Needle Creek Trail into Chicago Basin. From a Chicago Basin camp, the South Face route climbs toward the ridge between Sunlight and its neighbors, gaining the upper mountain on a mix of talus and broken rock. The final summit block is the route's crux: a short but genuinely exposed Class 4 move is needed to stand on the true high point. Many parties choose to stop on an adjacent, easier point just below rather than commit to this final move — know before you go which summit you're aiming for.
Reverse the route with particular care on the summit block down-climb, then return to camp and eventually to Needleton to flag down the train.