Pornainen, or Borgnäs in Swedish is a municipality of Finland.
It is located in the province of Southern Finland and is part of the Uusimaa region. The municipality has a population of 4,569 (2004-12-31) and covers an area of 150.05 km² of which 3.42 km² is water. The population density is 31.16 inhabitants per km².
The municipality is unilingually Finnish.
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