Palcacocha Lake, Glacial lake in the Cordillera Blanca, Ancash, Peru

Palcacocha Lake is a glacial lake in the Cordillera Blanca at about 4,566 meters elevation, surrounded by Palcaraju and Pucaranra peaks in Ancash province. Today the lake is fitted with monitoring stations and drainage pipes to manage water levels and prevent flooding in the communities below.

The lake formed from glacier melting and erosion over thousands of years in the high Andes. In December 1941, a massive piece of glacier collapsed into the water, triggering a devastating mudslide that destroyed parts of Huaraz city downstream.

The name Palcacocha comes from Quechua: pallqa or p'alqa, meaning forked or branched, and qucha, lake. The lake lies within Huascarán National Park, a protected natural area, and is one of several lakes that supply water to Huaraz, 23 km to the southwest.

The lake sits at high elevation and is reachable only on foot over steep mountain trails, usually with a guide. Visitors should prepare for thin air, cold temperatures, and weather that changes quickly at this altitude.

A resident of Huaraz sued a major energy company, connecting the company's greenhouse gas emissions to the increased flood risks created by this lake. This case became one of the first legal efforts to hold a corporation responsible for its role in climate change affecting a mountain community.