Sipoo is a municipality of Finland. It is part of the Helsinki metropolitan area. The municipality has a population of 22,840 and covers an area of 698.60 square kilometres of which 358.97 km2 is water. The population density is 67.24 inhabitants per square kilometre. The administrative center of the municipality is Nikkilä, which is located 34 kilometres northeast of the center of Helsinki. Another significant urban area is Söderkulla, located in the southern part of the municipality.