Battle of Nesjar (Slaget ved Nesjar) was a sea battle off the coast of Norway in 1016. It was a primary event in the reign of King Olav Haraldsson (later Saint Olav). Icelandicskald and court poet Sigvatr Þórðarson composed the poem Nesjavísur in memory of the battle.
Historic record
Tradition places the location of the battle in west end of Oslofjord. The exact location is unknown, but it is somewhere in today's Langesundfjorden inlet in Frierfjord near Brunlanes, Larvik in Vestfold. The fighting parties were the throne claimant Olav Haraldsson on one side and an alliance backing the Swedish vassal Sveinn Hákonarson on the other.