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.

Southern Norway is the geographical region (landsdel) along the Skagerrak coast of southern Norway. The region is an informal description since it does not have any governmental function. It roughly corresponds to the old petty kingdom of Agder being coextensive with the county, as well as the two former counties of Vest-Agder and Aust-Agder. From New Year 2020, the two counties have been merged into one county, Agder. The total combined area of Vest-Agder and Aust-Agder counties is 16,493 square kilometres (6,368 sq mi). The name is relatively new, having first been used in Norway around 1900.