There is also this small train station in Kotka. There is not real direct connection between Kotka and Helsinki and if you use the train, it will take you more time then the bus ride and you will need to change trains in Kouvola.
Most convenience way to get to Kotka is by driving. In the past the road was not that good, but now the road has been improved a lot and part of it is even motorway, it is only 130 km from Helsinki and as you see in this road sign, on my way, was only 300 km from St Petersburg.
Hitchhiking it is not very common in Finland, but apparently it is possible, especially if you are young and beautiful LOL
This lovely girl was joining us for the road back from Kotka to Helsinki.
There is regular bus line between Kotka and Helsinki. Buses are running all day long first bus at 6:30 in the morning and last bus at 23:00. The journey takes about 2 hours.