This journey over the highest rail crossing of the Andes takes you up to 15,688ft at Galera, and oxygen is available on the train. Once a daily train, it now operates about twice a month, though the carriages have been recently refurbished with windows in the roof and better seats.
Where Journey Latin America (020-8747 8315; www.journeylatinamerica.co.uk)
How much from £271
How long 3 days