The Ten Thousand Islands are a chain of islands and mangrove islets off the coast of southwest Florida, between Cape Romano (at the southern end of Marco Island) and the mouth of Lostman's River. Some of the islands are high spots on a drowned shoreline. Others were produced by mangroves growing on oyster bars. Despite the name, the islets in the chain only number in the hundreds..
The northern part of the Ten Thousand Islands, between Cape Romano and Everglades City, is in the Ten Thousand Island National Wildlife Refuge. The southern part of the Ten Thousands Islands, south of Everglades City, is in Everglades National Park. The 99-mile long Wilderness Waterway begins at Everglades City and ends at Flamingo at the southern tip of the Florida peninsula. Administrative control of the islands is split between Collier County and Monroe County.