The Manatee River is a 36-mile-long (58 km) river in Manatee County, Florida. The river forms in the northeastern corner of Manatee County and flows into the Gulf of Mexico at the southern edge of Tampa Bay.Wildlife in and around the river includes alligators, herons, manatees, dolphins, and fish such as bass, bluegill, catfish, and gar. Bull sharks are occasionally found in the brackish water near its low-lying outlet. The river includes the Upper Manatee River Canoe Trail for paddlers.