the country is in the atlantic ocean, near the western edge of the sargasso sea. it is about 580 nautical miles (1070 km, 670 mi) east-southeast of cape hatteras on the outer banks of north carolina and about 590 nautical miles (1100 km, 690 mi) southeast of martha's vineyard. the island is due east of fripp island, south carolina. it has 103 km (64 mi) of coastline.