The Bric Tana regional park covers a karst plateau immediately north of Millesimo. It is a tangle of sinkholes, doline depressions, and small caves cut into the limestone, with chestnut and beech woods on top.
Marked walking routes lead in from the edge of town. The signature loop takes a couple of hours and passes the larger sinkholes; with a torch you can look down into several of the cave entrances. It is also a notable site for cave-adapted invertebrates.