The Mina Chiflón del Diablo is a naturally ventilated undersea mine that operated between 1852 and 1976. Ex–coal miners now work as guides on well-organized 45-minute tours (Spanish only) that take you through a series of galleries and tunnels to a coalface some 50m under the sea.

Before clambering into the rattling metal-cage elevator that takes you down, you’re kitted out with safety gear. You can also visit the Pueblito Minero, painstaking re-creations of typical miners’ houses built for the Chilean movie Sub Terra (Underground), which was filmed here.