Rockville is located on Wadmalaw Island in southwestern Charleston County at (32.602932, -80.196942),[REF] at the south end of South Carolina Highway 700, on the north bank of tidal Bohicket Creek, an arm of the North Edisto River.
According to the United States Census Bureau, the town has a total area of , of which is land and , or 17.52%, is water [REF].