From the Las Pailas ranger station, you have several walking options, with trails leading west to the cataratas escondidas (hidden waterfalls) and east to the Santa María station, along an eight-kilometre path. The most popular and least demanding trail heads east on a very satisfying six-kilometre circuit past many of the highly unusual natural features with which the park abounds, including a mini-volcano and “Pilas de Barro” mud pots; listen out for strange bubbling sounds, like a large pot of water boiling over. Mud pots, which should be treated with respect, are formed when mud, thermally heated by subterranean rivers of magma, seeks vents in the ground, sometimes actually forcing itself out through the surface in great thick gloops. It’s a surreal sight: grey-brown muck blurping out of the ground like slowly thickening gravy. Another feature is the geothermal hornillas (literally, “stoves”), mystical-looking holes in the ground exhaling elegant puffs of steam. You almost expect to stumble upon the witches of Macbeth, brewing spite over them. Make sure not to go nearer than a metre or so, or you’ll be steamed in no time. The combined effect of all these boiling holes is to make the landscape a bit like brittle Swiss cheese – tread gingerly and look carefully where you’re going to avoid the ground crumbling underneath you. Many hikers have been scalded by blithely strolling too close to the holes. The trail also takes you through forest with abundant fauna and flora and be prepared to ford a couple of streams.