The Santa Fe River is typical of many rivers in karst regions in that it completely disappears underground and then reappears 5 kilometres (3 mi) downstream.[3] The river drops into a large sinkhole in O'Leno State Park[4] and reappears in the adjacent River Rise Preserve State Park.[5] The land over the underground section of the river, referred to as a natural bridge, was used for the main route of the Spanish mission trail and the Bellamy Road to avoid a water crossing of the Santa Fe River.[6]