This route is includes the largest sustained climb from El Chalten to Paso del Viento and is a portion of The Huemul Circuit. It's called one of Patagonia's lesser-known treks, but it should also be known as its hidden jewel of technical trail running.
The route begins at the Centro de Visitantes, Guardaparque Ceferino Fonzo, Parque Nacional Los Glaciares at the southern end of El Chalten.
The first 11 miles involve a sustained climb through forest and meadow that is intermittently (but mostly) runnable, followed by a pleasant downhill into a flat glacial basin. The trail continues across small streams on beautiful, but sometimes difficult to follow trail, although cairns are present to guide attentive runners. At 11 miles, there is a small campsite which you pass to continue on toward a small lake. At the terminus of the lake, the trail continues up and over some rocky terrain marked by more cairns to a large river crossing. A tyrolean traverse has been erected to accommodate passage across the large rapids which a runner must cross in order to continue. On some mornings, water flow can be milder and it is possible to ford the river upstream on foot and then connect with the trail, but it is not recommended to cross the river in the afternoons due to increased glacial melt. Once a runner crosses the river, the trail ventures toward a large glacier on very rocky and unstable terrain. However, it is still possible to move quickly in this section with surefootedness and high awareness of one's surroundings, as rockfall is common here from the pass above. The trail then descends slightly onto the glacier for about 600 meters and then hops back up onto the rocky slope toward Paso del Viento. The trail climbs to the Paso del Viento on a fairly obvious path, with a summit yielding a view of the Southern Patagonian Ice Field. To complete the out and back, descend along the same path as you come all the way back to the Park at the southern end of El Chalten. The total out & back distance is about 32 miles.
The Park Service for this area requires that you travel with equipment for a tyrolean traverse (harness, slings, steel locking carabiner), and also requires you to have a jetboil and park map to register for the trail. The Park Service requirements have changed frequently, so check in with them on what you need a few days prior to your attempts to ensure more requirements have not been added.
