Lapua is a town and municipality of Finland. It is located next to the Lapua River in the region of South Ostrobothnia. The town has a population …Lapua is a town and municipality of Finland. It is located next to the Lapua River in the region of South Ostrobothnia. The town has a population of 14,033 and covers an area of 751.82 square kilometres of which 13.67 km² is water. The population density is 19.04 inhabitants per square kilometre. The municipality is unilingually Finnish.