The Helsinki-Vantaa airport is located about 20 kilometers from downtown Helsinki. Taxi stands are located outside the arrival areas of the terminals. A taxi journey between the airport and downtown takes about 20-30 minutes, and costs about 40-45 EUR. Local trains (lines I and P) operate between the airport and the main railway station of Helsinki. The cost (for one-way ticket) is about 5.50 EUR and the journey takes about 35 minutes once you are on the train. Tickets must be bought from vending (ticket) machines before entering the train. Schedules are available at the HSL web pages. In general, the Journey Planner is a useful tool for public transport. Buses and in particular the Finnair City Bus operate between downtown Helsinki and the Helsinki airport. Finnair City Buses depart every 20 minutes, and tickets (6.70 EUR for a one-way ticket) are sold in buses.
Arriving by train to Helsinki, we recommend to get off at the Central Railway Station (marked with red #2 in the map below). Most long-distance busses stop in the Kamppi bus terminal (red #3 in the map below). Both the Main railway station and Kamppi bus terminal are within walking distance from the conference venue.
Public transport in Helsinki is extensive and includes busses, trams, metro, commuter trains and ferries. The most convenient form of transport downtown is trams. The above map shows the tram stops closeby the conference venue. More information: https://www.hsl.fi/en/tickets-and-fares