The Porsgrunn River is a river located in Norway, flowing through the town of Porsgrunn in the Telemark region. It is approximately 30 kilometers long and serves as an important waterway for the area, connecting to the Telemark Canal and eventually leading to the Skagerrak strait. The river is known for its scenic beauty and recreational opportunities, including fishing and kayaking. It plays a significant role in the local ecosystem and has historical importance, as it has been used for transportation and industry since the early days of settlement in the region.