The Cerro Castillo Trek in Aysen

Distance 10.6 miles (17 km) 

Elevation 1312 ft (400m) ascent, 0 ft (0m) descent

The first day of the Cerro Castillo National Park Trek traditionally starts outside the park boundaries. The route follows an old logging road, passing small estancias and herds of cattle, until the old rancher’s fences disappear and you reach the office of CONAF, the national park authorities, at Las Horquetas: the trailhead proper where you sign in and enter the park.

The trail winds in and out of the forest, occasionally opening up for brief mountain views before disappearing into the trees. You follow a valley and make several river crossings – prepare to get wet, although it’s unlikely the water will come up to your knees.

Only in the last hour of the hike do you get the big reveal of what you are trekking for, when the great snowy ramparts of the Cerro Castillo massif reveal themselves as you climb to the edge of the tree line.

Home for the evening is the rustic Camp Turbio amid the trees.

Distance 7.5 miles (12 km) 

Elevation 2910 ft (887m) ascent, 1883 ft (574m) descent

On the second day of the Cerro Castillo National Park Trek, the trail begins to steadily climb into the mountains. The first section follows the Turbio River through its valley, before you must lift your head and fix your gaze on Pẽnon Pass (4265 ft/1300m).

The ascent here is slow but steady, but the local geography means that there’s often snow here even quite late into the season. The descent is steep and on loose scree, and you’ll be torn between concentrating on your feet and the views as the route tracks close to the Peñon hanging glacier.

You’ll be able to stop at Laguna Tempanos, also known as the Iceberg Lagoon, fed by the glacier: as picturesque a spot for lunch as anywhere in Patagonia.

From here, it is a gentle downhill walk to Camp Bosque, where you’ll set up tents for the night.

Distance 5.6 miles (9 km) 

Elevation 3727 ft (1136m) ascent, 2992 ft (912m) descent

The third day of the Cerro Castillo National Park Trek has the steepest climb of the trek, as you tackle the Morro Negro Pass (5577 ft/1700m).

The route takes you via one of the National Park’s gems: Lake Cerro Castillo, an azure lake surrounded by a ring of mountains and fed by hanging glaciers, and a wonderful place to linger. 

After a picnic, the dry rocky climb to Morro Negro begins. The views when you reach the pass are incredible: a seemingly endless panorama of peaks, lakes and glaciers. As you see the mountains in the distance get lower, browner and snow-free, you’ll know that you’ve mentally crossed the invisible border into Argentina.

From here, it’s a fairly continuous descent along scree until you reach Camp Porteadores camp near the river. 

Distance 6.2 miles (10 km) 

Elevation 935 ft (285m) ascent, 2838 ft (865m) descent

The final day of the Cerro Castillo National Park Trek has you leaving your gear at the campsite to walk to a slightly higher campsite at Camp Neozelandes. This offers amazing views of the north face of the Cerro Castillo massif and its glacial basin. It’s an easy diversion from here to walk to Laguna Duff, another beautiful glacial lake.

From here you’ll follow an easy and steady descent through light and open lenga forest, with constant views of the mountains. It’s a relatively short walk to arriving back at Camp Porteadores to pick up your pack.

The trail continues through open country until you reach the limits of the national park. If you don’t have your own transportation you’ll need to walk the rest of the way to get back to Villa Cerro Castillo, otherwise you can rest your legs as you take a transfer back to your accommodation for a shower, a change of clothes and a celebratory meal.