Nastola is a former municipality of Finland. It was merged with the city of Lahti on 1 January 2016. In the province of Southern Finland, Nastola is part of the Päijät-Häme region. The municipality had a population of 14,905 and covered an area of 382.86 km2 of which 38.67 km2 was water. The population density was 45.9761/km2. Nastola is located between two major cities: Lahti and Kouvola.