Seabrook Island, formerly known as Simmons Island, is a barrier island in Charleston County, South Carolina, United States. The population was 1,714 at the 2010 census, up from 1,250 in 2000.
Seabrook Island is part of the Charleston-North Charleston-Summerville metropolitan area.
Seabrook Island is located in southwestern Charleston County at 32°34′56″N 80°9′48″W (32.582173, -80.163332), bordered to the south by the Atlantic Ocean, to the west by the North Edisto River, and to the north by Bohicket Creek. The he east along the Atlantic shoreline as far as the Kiawah River, across which is the town of Kiawah Island. Most of the eastern border of the town, however, is next to unincorporated land. The city of Charleston is 25 miles (40 km) to the northeast.
According to the United States Census Bureau, the town of Seabrook Island has a total area of 7.0 square miles (18.1 km2), of which 6.0 square miles (15.5 km2) is land and 1.0 square mile (2.7 km2), or 14.74%, is water.
The Köppen Climate Classification System rates the climate of Seabrook Island as humid subtropical. Ocean breezes tend to moderate the island climate, as compared to the nearby mainland were daytime highs are higher and nighttime lows are lower. Daytime mean highs in winter range from 55 to 60 °F (13 to 16 °C), with nighttime lows averaging 43 to 50 °F (6 to 10 °C). Summertime mean highs are 85 to 88 °F (29 to 31 °C), with average lows 74 to 76 °F (23 to 24 °C).