Vinicunca — Rainbow Mountain — is the striped ridge 100 km southeast of Cusco. Iron oxide, copper and iron sulphide in sedimentary rock produced the colours over tens of millions of years; glacial retreat around 2015 made the slopes visible from the valley below.
Peruways runs day trips with 3am departures from Cusco, a three-hour drive and a 3 km one-way walk from the trailhead at 4,800 metres to the viewpoint at 5,036 m. The altitude is the main challenge — horses are available on the steep sections for around 100 soles.
Guides add the Red Valley detour (quieter striped ridge, 20 minutes off the main viewpoint), Quechua place names, and the geology of why the colours form in bands rather than patches.
Book at Peruways, acclimatise in Cusco for two or three days first, and target the dry season (May–September) for the sharpest colours.
