 According to the United States Census Bureau , the city has a total area of 497 square miles ( 1 @,@ 290 km2 ) , of which 249 square miles ( 640 km2 ) is land and 248 square miles ( 640 km2 ) ( 49 @.@ 9 % ) is water . It is the largest city in Virginia by total area and third @-@ largest city land area . The average elevation is 12 feet ( 3 @.@ 7 m ) above sea level . A major portion of the city drains to the Chesapeake Bay by way of the Lynnhaven River and its tributaries . 
