Gandy Bridge is the southernmost bridge spanning Old Tampa Bay from St. Petersburg, Florida to Tampa, Florida. The original 1924 span was dismantled in 1975. The second bridge, constructed in 1956 was used for vehicular traffic until 1997, when it was converted to recreational use by non-motorized traffic. It became known as the Friendship Trail Bridge and was demolished in 2016, after closing in 2008 due to hazardous conditions and several failed efforts to preserve the span. The third (1975) and fourth (1997) spans of the Gandy Bridge are currently being used for vehicle traffic.

Tampa Bay is a large natural harbor and shallow estuary connected to the Gulf of Mexico on the west-central coast of Florida, comprising Hillsborough Bay, McKay Bay, Old Tampa Bay, Middle Tampa Bay, and Lower Tampa Bay. The largest freshwater inflow into the bay is the Hillsborough River, which flows into Hillsborough Bay in downtown Tampa. Many other smaller rivers and streams also flow into Tampa Bay, resulting in a large watershed area.