Tampa Bay, inlet of the Gulf of Mexico, 25 mi (40 km) long and 7 to 12 mi (11.3–19 km) wide, W Fla., separated from the Gulf by numerous small islands; it receives the Hillsborough River. St. Petersburg is on the western neck, Old Tampa Bay, and Tampa is on Hillsborough Bay, the eastern neck. Tampa Bay has dredged shipping channels. Spanish explorers Pánfilo de Narváez (1529) and Hernando De Soto (1539) landed at Tampa Bay. It is spanned at its mouth by the Sunshine Skyway Bridge.