The municipality has a population of 18,776 (30 September 2012) and covers an area of 698.59 square kilometers (269.73 sq mi) of which 358.97 km2 (138.60 sq mi) is water. The population density is 55.29 inhabitants per square kilometer (143.2 /sq mi).
The once almost completely Swedish-speaking municipality is since 1953 bilingual, a majority being Finnish speakers since 2003, due to migration from other parts of Finland. Today the Finnish-speaking majority stands for ca 60% and the Swedish-speaking minority for about 39% of the population
