The Everglades is a natural region of tropical wetlands in the southern portion of Florida, comprising the southern half of a large drainage basin and part of the neotropic ecozone. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee. Water leaving the lake in the wet season forms a slow-moving river 60 miles wide and over 100 miles long, flowing southward across a limestone shelf to Florida Bay at the southern end of the state. The Everglades experience a wide range of weather patterns, from frequent flooding in the wet season to drought in the dry season. The Seminole Tribe gave the large body of water the name Okeechobee meaning "River of Grass" to describe the sawgrass marshes, part of a complex system of interdependent ecosystems that include cypress swamps, the estuarine mangrove forests of the Ten Thousand Islands, tropical hardwood hammocks, pine rockland, and the marine environment of Florida Bay.