Adventfjorden

[Image:Spitsbergen labelled.png|thumb|350px| Adventfjorden lies on the southern side of Isfjorden on Spitsbergen's west coast.]
Adventfjorden is a 7 km long and 4 km wide bay running south-eastwards from the southern side of Isfjorden, on the west coast of Spitsbergen in Svalbard. The name represents a corruption of Adventure Bay - probably named after the Hull-built whaleship Adventure, which operated in Isfjorden in 1656. The fjord was originally known as Klass Billen Bay. At the head of Adventfjorden is Adventdalen.
The former mining-camp of Longyearbyen lies on the fjord's southwestern shore, while another former mining-camp, Hiorthhamn, is located on its northeastern shore.