A long limestone cave system about 200 kilometres southeast of Kunming, near the town of Luxi, Alu Ancient Cave is one of the more impressive karst caves in southern China — over three kilometres of passages on multiple levels, with three "dry" galleries and one through which an underground river flows. Skylights in the cave roof let in shafts of natural light in places, which is unusual.
A boat trip on the underground river is the standard experience and gives the cave its character. The drive from Kunming is long, however, and Alu is realistically a stop on the route between Kunming and the Yuanyang rice terraces rather than a half-day trip out and back.