The fjord is generally about 3 to 5 kilometres (1.9 to 3.1 mi) wide. There is only one crossing: a car ferry from StĂ¸vĂĽg in Gulen to Mongstad in LindĂĽs. The islands of ByrknesĂ¸yna, MjĂ¸mna, and SandĂ¸yna (as well as the mainland) lie on the northern side of the fjord. The south side of the fjord includes the island of FosĂ¸yna and the LindĂĽs peninsula lie on the south side of the fjord.
There is a lot of ship traffic in the outer part of the Fensfjorden due to the large oil refinery and industrial area at Mongstad on the northern end of the LindĂĽs peninsula. Mongstad is Norway's largest port based on tonnage, and Northern Europe's largest oil port. Roughly 2000 ships port at Mongstad in the Fensfjorden annually.