Helsinki Airport consistently ranks among the best airports in the world and serves around two hundred international flights each day. The journey time between the airport and city centre is around 25 minutes.
There are daily ferry services to Helsinki from Estonia and Sweden, see e.g. Tallink Silja Line, Viking Line or Eckerö Line, as well as from Germany by Finnlines. All the ferry companies offer also possibility to take a car with you. Helsinki can be reached by ferry also from Russia by St. Peter Line as well as from Poland.
More information can be found at Visithelsinki -portal.