So we have another of those many celebrations arising from pagan roots within our midst. While the summer solstice marks the longest day of the year on June 20; Midsummer Day falls within the purview of the old Julian calendar where it was on the different date of June 24.
This is a time to celebrate what many feel is the best time of the year. In addition another aspect of the pagan derivation of Midsummer Day is the celebration of harvest and fertility as well as that summer solstice which remains the longest day of the year — but it also involves the celebration of life and love.
Traditions of Midsummer Day are primarily of Scandinavian origin like the countries of Sweden and Finland — and include song and dance the day before which is known as Midsummer Eve. There is also the jumping over bonfires, searching for the magic fern flower at midnight, and washing the face with morning dew to greet the midsummer sun.
The day also celebrates the memory of John the Baptist — whose birthday falls during this time. There is also Nightless Night which is characterized by a belief in witches, fairies, and elves who descend on Earth and pursue we humans.
Estonia refers to this day is known as Jaanipäev aka Jaan's Day and is celebrated on Midsummer Eve.
It's all very festive and social in it's various aspects and I would certainly enjoy the chance to participate one day should the opportunity arise.