Leaving early from San Fabián, we will follow by vehicle the beautiful Ñuble river towards the border with Argentina, and then its tributary the Los Sauces river until we reach the town of Pichirrincón. Here we will leave our vehicles and prepare to start our great adventure. We will start walking on a vehicular path that can only be accessed by 4×4 for the first 1.5 kilometers, before attacking the steep climb through an oak forest (Nothofagus obliqua). Arriving at an esplanade that was formerly used by muleteers as a summer sector, we will take the time to hydrate and rest. Then we will continue for approximately 4 more kilometers, crossing oak forests, ancient lava rivers, coironales and ñirres forests (Nothofagus antarctica) in the last sections prior to arriving at the lagoon. After about 4-5 hours of ascent, you will be able to contemplate the beauty of the lagoon from the top of a hill. We will skirt the lagoon to one of its beaches, where we will set up our camp and spend the night under the stars. It is essential to take into consideration when setting up a camp several of the Do Not Leave a Trace principles, principles that we will explain in the place and that will help us to generate the least possible impact on the natural environment. If the weather permits, we can swim in the lagoon. During the night we can observe the milky way and the constellations present, and take astrophotography. The next day in the morning, we will be able to enjoy a sunrise in the mountain range, rest or go up to the viewpoints that are in the hills that dominate the lagoon, offering spectacular views over the Domuyo volcano, the Nevado de Chillán and the beautiful Sierra Huemules. . After lunch we will raise our camp and begin our return journey, along the same path as the climb.