Trek El Cerro Castillo in Patagonia

El Cerro Castillo trek is usually done from East to West, from Las Horquetas curve on route #7 to Villa Cerro Castillo. The reason behind that is because it is easier to reach Las Horquetas sharp curve than leaving it, but also because the view gradually gets better and better that way.

When leaving the curve, walk slightly down and follow the river. You'll see a little wooden cabin away. That's the ranger station, and depending on the season, the day or the hour, you might have to pay your way in ($5,000CLP).
Once that's done, you will immediately get welcomed on the Cerro Castillo trail by having to cross a river using a very artisanal home-made wooden bridge.

Just follow the obvious trail (on which 4x4 can go) after that. It will follow the river for a just a while before turning left.
You will go through some prairie on which cows might be chilling, followed by a non-inviting forest (just like they draw them in children's books). The forest will eventually become very welcoming. Stay on the tracks and except to cross a few more streams (requiring to take your shoes off).
You'll go deeper in the forest and end up reaching a ranger's cabin and camping spot. The entire thing seems to have been abandoned. That aside, this is not where you want to camp (no rivers, no views, too shady). Just before that you'll also have come across and intersection with a trail going right (West-NorthWest), disregard it and keep walking south towards the ranger hut.
Keep walking for only another 1.3miles and you'll reach the "Segundo Camping" located right next to a river bed with great valley views, which is a way nicer spot to put your tent.

Just 1.3 miles after that camping spot, you'll reach a hard to see intersection, with a trail going right towards a rocky moraine.
This is a go-and-back trail of 2miles total (1mile each way), leading to a glacier lake with some pretty sweet peaks in the background. Worth the detour. Just be careful as the path can be hard to find on the way back. Make visual notes when walking in.
Once you're back on the intersection, follow the main trail again going up in the forest. The path will get slightly steeper as you get out of the forest and start walking through rocks instead of ground. You will reach a flat pass with, depending on the season, some snow patches here and there.
A treacherous and dangerous way down is expecting you right after that pass. Be very careful as the trail is narrow, steep and extremely exposed to wind. Deaths by falling have been reported.

No need to panic. Just pay attention where you put your feet.

Once done with that hike down, keep walking until you reach the forest. From there and for the next 1mile the hike is mostly down with a small way up at the end, where you'll reach the "El Bosque" campground.

You can either stay there (which I don't recommend because the view sucks and it's very shaded) or keep walking 1.5miles and 1,000ft up through the forest to reach the much much better "La Tetera" campground. Do it!

Once you get to La Tetera campground (which is very spread around, don't limit yourself to the first spot you see), you're just 5min away from the Laguna Castillo, a turquoise glacier lagoon which will be one of the highlights of your trip.
Don't hesitate to wander around and even go up the Morro Rojo (the red mountain right next to you, can't miss it).

Once you're done with the area you can either give up and take the emergency exit to go back down to Villa Cerro Castillo or keep going for more astonishing landscapes. Either way you'll have to go up the rocky section located south of the lagoon. The path is hard to find, so just go up however you want.
You'll then reach an intersection with a trail going back down on your left, or going straight up for another 1,000ft of elevation.
Go straight and get blown away by the view. Stop been mesmerized every 2 minutes and keep moving.

After reaching the highest point, a 2,600ft hike down over 1.8miles (which equals to an impressive 26% steepness!) is expecting you.
Halfway down, should the weather allow it, and even though you shouldn't -but who knows, maybe you hurt yourself and need an overnight rest?- locate a flat spot near the boulder and put your tent. Otherwise, keep going down through the forest and as soon as you reach the intersection, go right to reach the "Los Porteadores" campground. Or, option 3, keep walking through the not so flat campground and walk all the way to the "Neo-Zelandes" campground, located 2.2miles and 850ft up after that. You will however have to walk that same path back again since it's a go-and-back trail to the Neo-Zelandes campground from the intersection. But there's a few more lagoons to see from there.

Once you're back on the intersection, just keep walking down for another 2.8miles and 900ft of negative elevation.

The end is a bit confusing as you're going right between private properties with 4x4 tracks going a bit everywhere and an endless fence along the road.

If like me you couldn't find the way out of the fence, maybe you got lost, but just find a spot where you can jump over it.

This is not over yet, as you still have 4miles to walk on a flat dirt road until you reach the Villa Cerro Castillo Town.