The Galveston Bay system consists of five subbays: Christmas Bay, West Bay, Lower Galveston Bay, Upper Galveston Bay, East Bay, and Trinity Bay. The bay is fed by the Trinity River and the San Jacinto River, numerous local bayous and incoming tides from the Gulf of Mexico. The bay covers approximately 600 square miles (1,500 km²), and is 30 miles (50 km) long and 17 miles (27 km) wide. Galveston Bay is on average 7-9 feet (3 m) deep. The bay has three inlets at the Gulf of Mexico: Bolivar Roads (the exit of the Houston Ship Channel) between Galveston Island and the Bolivar Peninsula, San Luis Pass to the West, and Rollover Pass to the East.
The bay provides nursery and spawning grounds for large amounts of marine life, and is important for both commercial and recreational fishing.citation needed
