The Thirty Thousand Islands is the world's largest freshwater archipelago, and are located mainly along the east side of Georgian Bay, part of the Great Lakes, in Ontario, Canada. UNESCO designated the area in 2004 as the Georgian Bay Littoral (also called the Georgian Bay Biosphere Reserve). It is an area of 347,000 hectares (860,000 acres) that stretches 200 kilometres (120 mi) along the eastern coast from Port Severn to the French River.