The Santa Cruz Trek crosses the highest tropical mountain range on Earth in four days and never once asks for a rope. Fifty kilometres of trail link the villages of Vaquería and Cashapampa through the Cordillera Blanca of northern Peru, under ice faces that go past 5,800 metres. Nothing about the walking is technical. The air is: the route spends its days high, topping out at 4,750 metres, so most people give Huaraz two or three nights first and set off slowly. Mule trains do the carrying. The arrieros who drive them have been crossing these passes far longer than the trekkers have, at a steady unhurried pace, and hiring one leaves you with a daypack and nothing else on your back.
The first days climb the Huaripampa valley through open grassland and stands of queñua, red papery trunks alive above 4,000 metres where no other tree manages. Camp at Taullipampa sits directly under the fluted ice wall of Taulliraju, which cracks and settles through the night. Tents freeze hard by morning. A half-day from that camp puts you at the foot of Alpamayo and Quitaraju, the ice pyramids the main trail only shows from a distance. Lower down, the path runs beside Ichiccocha and Jatuncocha, twin lakes so loaded with glacial silt that on a still morning the peaks lie doubled on them. Across the trough where Huaraz sits stands a second range with no permanent snow at all, the Cordillera Negra, which never rises high enough to hold a glacier: the black range, named against the white one you are walking in. The high point of the route is a gap in the rock at 4,750 metres, Punta Unión, barely wide enough to take the trail. You step through it and the whole range arrives in the width of that gap: Taulliraju's ice close on one side, a green lake far below on the other.