Sipoo (Finnish pronunciation: [ˈsipoː], Swedish: Sibbo) is a municipality of Finland. Its seat is in Nikkilä/Nickby.It is the eastern neighbour of Helsinki and is located in the Uusimaa region. The municipality has a population of 19,235(30 June 2015) and covers an area of 698.59 square kilometres (269.73 sq mi) ofwhich 358.97 km2 (138.60 sq mi)is water.