Here you will find good information on how to travel to Finland
http://www.finland.com/comingto.do  

By car
There are three main options to travel to Finland by car:

By ferry from Stockholm (Sweden) to Turku or Helsinki. The ferry to Turku is cheaper than to Helsinki but then you have to drive a bit more: it is about 270 km from Turku to Heinola, and from Helsinki to Heinola about 150 km.

By ferry from Rostock (Germany) to Helsinki           
This is the easiest way to travel from Germany to Finland.

By ferry from Tallinn (Estonia) to Helsinki
Use Via Baltica –route to drive from Germany to Tallinn. Take a ferry to Helsinki.Via Baltica is the shortest route connecting Finland with central Europe through the three Baltic republics of Estonia, Latvia and Lithuania. The distance from the border of Poland to Tallinn is 670km.
See http://www.respons.pp.fi/viabaltica/engl/indexanglb.html and http://en.wikipedia.org/wiki/Via_Baltica  

Info about ferries:
http://www.tallinksilja.com/en/
http://www.vikingline.fi/index.asp?lang=en
http://www.eckeroline.fi/en/default.aspx
http://www.finnlink.fi
http://www.ferrycenter.fi/  

A good web-site to plan your route is http://www.viamichelin.com/  

We'll try to negotiate better prices with ferry companies. Please notice that tickets should be booked well in time before the actual travel. Please check these pages for possible offers before booking tickets. 

ROSTOCK-HELSINKI:
TallinkSilja offers cheaper tickets for route Rostock-Helsinki-Rostock. The better price will be informed to the representative of each country with instructions on how to book the tickets. This offer is only for people coming to this event and is valid in time period of week before and week after the race. For more info, please contact Jorma Korhonen, the country representative of Finland: jormakorhonen(at)kolumbus.fi

Flying to Finland:

One option to be considered is that you put as many bikes and other things as possible in one big car, and then most of the people fly to Finland. Although faster, that could even be much cheaper than to come with a car. Especially if the tickets can be booked early enough. For example, Ryanair has sold tickets from Bergamo, Italy to Tampere and back from 70 euros per person! And that’s really a return price. Same thing from Stansted, London and Frankfurt-Hahn and Bremen in Germany. 

The main airport is Helsinki-Vantaa http://www.helsinki-vantaa.fi/home
From here you can rent a car and come easily to Heinola (travel time about 1½ hours). Or you can use busses (travel time about 2½ hours). Please notice that there is no railway connection to Heinola. 
Some links to rent a car from Helsinki-Vantaa airport:
Car rental Bevari
Finn car rental
AutoAlex
Budget
EasyTerra
Smart travel (used cars, cheap rates, not from airport)

Another airport is in Tampere which for example low fare airline company Ryanair uses http://www.finavia.fi/airport_tampere-pirkkala It takes about 30 minutes by bus from airport to city centre. From Tampere it is about 190 km to Heinola.  
Some links to rent a car from Tampere:
Rentcenter
Avis
Budget
Finn Car Rental

For airline companies, see for example
http://www.finnair.fi/
www.blue1.fi/en/
http://www.ryanair.com/ 

General info about Finland, traveling etc. 
Virtual Finland – your window on Finland. From here you can find almost everything about Finland  http://virtual.finland.fi/Travel/

Visit Finland: here is a lot of info in many different languages:
http://www.visitfinland.com/w5/index.nsf/(pages)/index