One of the largest undisturbed tropical rain forest areas in Central America is the Columbia Forest Reserve. It's in a remote area north of San José Village. The karst terrain—an area of irregular limestone in which erosion has produced sinkholes, fissures, and underground streams and caves—is difficult to navigate, so the only way to see this area is with a guide and with advance permission from the Belize Forestry Department. It has extremely diverse ecosystems because the elevation ranges from about 1,000 to over 3,000 feet, with sinkholes as deep as 800 feet. You'll find areas of true "high bush" here: old-growth tropical forest with parts that have never been logged at all. Much of the rich flora and fauna of this area has yet to be documented. For example, one brief 12-day expedition turned up 15 species of ferns never found before in Belize, along with several new species of palms, vines, and orchids. Check with the Toledo Tour Guide Association at the BTIA visitor information office in Punta Gorda to try to find a guide to take you to this remote reserve.