The Penobscot River is a 109-mile-long (175 km) river in the U.S. state of Maine
. Including the river's West Branch and South Branch increases the Penobscot's length to 264 miles (425 km),making it the second longest river system in Maine and the longest entirely in the state. Its drainage basin contains 8,610 square miles (22,300 km2).
It arises from four branches in several lakes in north-central Maine, which flow generally east. After the uniting of the West Branch with the East Branch at Medway.Also at Bangor
is the tributary Kenduskeag Stream
. It empties into the Atlantic Ocean in Penobscot Bay. It is home to the Penobscot people that live on Indian Island.