Laguna Humantay

Laguna Humantay sits at 4,200 metres above sea level in a glacial cirque beneath the western face of Nevado Humantay, a 5,473-metre peak in the Vilcabamba range.

The lake owes its luminous turquoise colour to suspended glacial flour — fine sediment ground by the Humantay glacier and carried into the basin by seasonal meltwater. Geologists estimate the cirque was carved during the last glacial maximum, roughly 20,000 years ago, when the Salkantay massif supported a continuous ice sheet. Today the glacier has retreated more than 300 vertical metres since the first surveys in the 1970s, leaving the lake fed primarily by snowmelt and seasonal precipitation.

The trail to Laguna Humantay begins at Soraypampa, a high-altitude meadow at 3,900 metres that serves as the principal staging point for both day hikers and trekkers bound for the Salkantay Pass. The 1.8-kilometre ascent gains 300 metres over switchbacks cut into the scree slope, passing through puna grassland where vicuñas graze and Andean lapwings nest. The path was formalised in the early 2000s as part of regional conservation efforts led by the Mollepata District and the Cusco Regional Directorate of Culture. A 30-PEN conservation fee, collected at the trailhead, supports trail maintenance, waste management, and seasonal patrols that enforce camping restrictions around the fragile shoreline.

Laguna Humantay altitude requires acclimatisation. Medical studies conducted in Cusco recommend spending at least two nights at 3,400 metres before ascending above 4,000 metres. The lake's elevation places it within the physiological threshold where arterial oxygen saturation drops below 90 per cent in unacclimatised visitors, and acute mountain sickness affects roughly one in four hikers who arrive directly from lower elevations. The Peruvian Ministry of Health advises gradual ascent, hydration, and avoidance of alcohol for 48 hours prior to the trek.

The lake appears on satellite imagery as a 200-metre-wide oval, bounded on three sides by moraines and on the south by a vertical cliff of Ordovician slate. Its depth fluctuates seasonally, reaching a maximum of approximately 12 metres during the wet season from December through March. The Humantay weather system is dominated by orographic cloud formation, with morning clarity giving way to afternoon fog and occasional lightning storms above 4,000 metres. Temperature ranges from -5°C at dawn to 12°C by midday, even during the dry months of May through September.