Yeah - the Swedes do the maypole, but with a largish Swedish community on the west coast of Finland, some do it there also :)
ours is harvest festival being end of seasonal crops.
I don't think they have an end of season one - though there is an informal "venetsialaiset" event that marks the end of boating and summer cottage life before the winter :)
Regional traditions always interesting to learn about, each has their own carried down through generations.