The Finnish labor laws guarantee those working in Finland a good number of vacation days. Most of those are taken during the summer and in July in particular. If you are working in Finland, better get used to work stopping for a whole month at least during the summer.
Midsummer is an ancient celebration of fertility and good harvest. The celebration has had a Christian association from the Middle Ages, but the way Finns celebrate Midsummer one could never tell there’s anything Christian about the holiday at all!