All Scandinavian countries celebrate Midsummer. Because of our very northern location it is practically daylight in the middle of the night at this time of the year.
Midsummer is the time to enjoy the sunlight, family, good food, outdoors and generally it compresses everything about summer into festivities that last a couple of days.
Traditionally Finns spend it in the countryside, enjoying lakeside saunas etc. Nowadays more and more people live in an urbanized space so for those with the means and the possibility it is usual to go into the countryside. Others spend their summer in the city enjoying the calm that is not possible almost any other time except on Christmas Day.