In 1945 a farmer in the mountain hamlet of Venado fell into a hole, and thus discovered these eight subterranean, limestone chambers extending about 2½ km (1½ miles). Sunset Tours runs trips. If you're not claustrophobic, willing to get wet, and don't mind bats—think carefully—this could be the ticket for you. Rubber boots, flashlights, and helmets are provided.
45 mins north of La Fortuna and 20 mins southeast of San Rafael, La Fortuna, 21010, Costa Rica