There are numerous trails on St. John.  If you go hiking, wear sensible shoes and bring some water.  A very popular (but somewhat strenuous) hike is the Reef Bay Trail.  This goes past to the Reef Bay sugar mill ruins, and also near the ancient petroglyphs.  These pre-Columbian Taino carvings above a fresh water pool are from around 900 - 1500AD, and exemplify the designs found on ceremonial Taino pottery.  The pool and symbols were sacred to the Taino, and reflect the duality of the spiritual and living worlds often reflected in Taino art.