An illustration of the mouth of the Miami River. The Miami River is a river in Florida that drains out of the Everglades and runs through downtown Miami, Florida. The 5.5 mile (8.9 km) long river flows from the terminus of the Miami Canal at Miami International Airport to Biscayne Bay. It was originally a natural river inhabited at its mouth by the Tequesta Indians, but it was dredged and is now polluted because of its proximity to the Miami-Dade County. The mouth of the river is now home to the Port of Miami and many other businesses whose pressure to maintain it has helped to improve the river's condition.