Answer:
There are many differend traditional costumes in Finland. National Dresses or Kansallispuvut in finnish are widely presented in a nice web page. Link can be found below this text under 'Related Links'.
Unfortunately it's only in finnish but here ase some translations you might need:
- Maakunnittain = By province
- Paikkakunnat = District (City, town, municipality)
- Suomen kartta = Map of Finland (Suomi is Finland in finnish ;) )