Originally Posted by
House
Never used it, but are is (I believe) a couple of showers in the Long Haul Lounge near Gate 30. Six hours sounds like long enough to easily get into the city and back again.
As
House mentions there is a shower or two in the non-Schengen lounge near Gate 30. And if you are traveling from December onwards there will be a spa at the Airport too
http://blogs.finnair.com/2009/02/26/spa/ .
I would also recommend going Downtown as the Finnair Bus to the Railway Station takes only 30-40 minutes and the buses leave every 20 minutes. You'll easly have 3-4 hours in Helsinki for a nice lunch/dinner. Please give us some more details on your trip - the flights you're taking and when/which month so we could try to give you some better recommendations.