The Coastal Lowlands include Florida's coasts and the Florida Keys. The Keys are a chain of small coral and limestone islands off the southern coast. The lowlands also include a vast wetland south of Lake Okeechobee. It is known as the Everglades. Often no higher than sea level, these areas flood quickly during storms. On the coasts, the land is primarily sand, with windblown dunes, sandbars, and lagoons.