The Tagus is the longest river on the Iberian Peninsula, 626 miles long, of which 445 miles is in Spain, 29 miles is a shared border between Spain and Portugal and the remaining 171 miles are in Portugal. It is highly utilized along nearly all its length, with dams for drinking water reservoirs and hydroelectric generation. The wide estuary at the Atlantic Ocean end is a busy waterway surrounding the port of Lisbon. The estuary itself is a protected Natural Reserve. The Vasco da Gama Bridge, which crosses the estuary, is the longest in Europe at 10.7 miles.