Mäntyharju (Finnish pronunciation: [ˈmæntyˌɦɑrju], "Pine Ridge") is a municipality of Finland. It is located in the Southern Savonia region. The municipality has a population of 5,905 (31 January 2019) and covers an area of 1,210.98 square kilometres (467.56 sq mi) of which 229.23 km2 (88.51 sq mi) is water. The coastline is almost 1,520 kilometers (940 mi). The population density is 6.2 inhabitants per km². Neighbouring municipalities: Heinola, Hirvensalmi, Kouvola, Mikkeli, Pertunmaa and Savitaipale. The summer houses or cottages located in the countryside are part of the culture of Finland where most Finnish families spend their summer holidays. Mäntyharju is the municipality which has the fifth most summer houses in Finland. Some of the reasons for Mäntyharju's popularity involve its many pure lakes and a relatively short distance to the Finnish capital Helsinki of approximately 200 kilometres by car. The municipality also has a direct, high-speed train connection to the capital area. Because of the many summer houses, the population of Mäntyharju more than doubles during the most popular summer holiday times. Art Centre Salmela in Mäntyharju hosts one of Finland’s largest cultural events in July-August. The municipality is unilingually Finnish.