Arendal is a municipality in Agder county in southeastern Norway. Arendal belongs to the region of Sørlandet. The administrative centre of the municipality is the city of Arendal. Some of the notable villages in Arendal include Rykene, Eydehavn, Færvik, Strengereid, Kongshavn, Kilsund, Brattekleiv, Torsbudalen, Longum, Saltrød, Staubø, Vrengen, and Kolbjørnsvik. The offices of UNEP/GRID-Arendal are also located in the city of Arendal.

Hisøy is a former municipality in the old Aust-Agder county in Norway. The 10-square-kilometre (3.9 sq mi) municipality existed from 1881 until 1992 when it was merged into the municipality of Arendal in what is now Agder county. At the time of its dissolution, it was the smallest municipality in the whole county. The municipality encompassed the islands of Hisøya, Gjervoldsøy, Havsøya, Ærøya, Store Torungen, Lille Torungen, and several other small, unpopulated islands. The administrative centre was the village of Kolbjørnsvik on Hisøya island.