Huascaran

Declared in 1975, it protects the Cordillera Blanca, the highest tropical mountain range in the world, with 27 peaks above 6,000 metres, Huascarán itself (6,768 m) among them — the highest mountain in Peru. In 1970 an earthquake set off a massive avalanche from that same peak which buried the town of Yungay, killing over 20,000 people in one of the worst natural disasters in South American history, a tragedy that drove part of the area's later official protection. It has been a UNESCO Biosphere Reserve since 1977 and a World Heritage Site since 1985, and its network of turquoise glacial lakes — such as the celebrated Laguna 69 — draws walkers from around the world, though the accelerating retreat of its glaciers under climate change threatens the long-term water supply of the Andean communities that depend on the seasonal melt.