There’s some nice waterfront running in Skien, a town/city on the Skeinselva river, located 8 km north of Porsgrunn and considered part of the Porsgrunn/Skien metropolitan area. We’ve put together a loop along Hjellevannet Lake & the Skeinselva River and also along the east side of the Skeinselva River. There are paths most of the way, and some great views.

Klosterøya Island. Google Street View

Start at the Telemarkskanalen path and run south for 1.3 km on the path along the west side of Hjellevannet Lake, enjoying the nice water views. Then follow the road to cross the narrow Falkumelva River. Pick up the cycle path alongside the Elstrømbrua, a major road crossing the river/lake. The next 1 km is inland on a path alongside the Ulefossvegen. Then, head north onto Klosterøya Island, which has numerous water crossings, good views of the water & town, and additional paths.

Skeinselva River East Side: The main route is 7 km. As an add-on/alternative, there’s a nice 2.6 km out & back path along the east side of the Skeinselva River.