From the 1500's through the 1700's a natural land bridge served as a crossroad between the Santa Fe River Sink and the River Rise. Still in existence today, you can observe where the Santa Fe River disappears within O'Leno State Park, goes underground and then reemerges several miles away at River Rise Preserve State Park. Its flow is expelled from the underground unto the surface to continue its flow to the Suwannee River. This natural bridge was traveled by Spanish explorers, Indians and settlers alike.