Valborgsnatt

Valborgsnatt (lit. "Valborg's Night") is a festival celebrated on the night of April 30th and the day of May 1st. It coincides with Walpurgis Night, which is the Christian holiday celebrating the canonization of Saint Walpurga and the movement of her relics to Eichstätt, which occurred on May 1st. Valborgsnatt festival has taken its name from St. Walpurgia in modern times, though it is unrelated. Rather, Valborgsnatt is celebrated as a public festival to welcome the arrival of spring, the end of winter, and the coming year ahead.
Valborgsnatt is not traditionally celebrated in the family or small groups, but in large public celebrations, from sunset on April 30th to sunrise on May 2nd. It is common for local governments, councils, or other organizations to organize the festivities to promote community spirit and safety.
Breakfast traditionally consists of champagne, strawberries, and whipped cream. It is traditional to spray others with champagne, alcohol, or water, and it is also acceptable to similarly cover others in foods.
Bonfires (Majbrasor, lit. "May fires") are lit throughout the nights, and competitions may be held as to which fire burns the highest or longest. It has become a more modern convention to build bonfires that will burn in specific patterns, or with specific colors. For safety, most bonfires are regulated by the local government and inspected prior to being lit, and some localities require all bonfires to be built by local fire committees.
It is traditional for all local farms to release their animals, such as cows, pigs, horses, and sheep, with brightly colored powder in their fur. Each farm has its own pattern or color to this powder. Animals are allowed to graze in large, shared regions throughout the festivities. One animal from each herd that would otherwise be slaughtered that year is expected to be offered to the Völva for the Blót to Freyja on Valborgsnatt and the animals are cooked for the evening feasts that welcome all visitors.
Group potlucks, community feasts, and the sharing of small edible treats with anyone a person encounters have become local traditions. It is common for shops to sell Valborgnatt treats in individually packaging, as well as large, decorated bags, to facilitate the exchange of treats between everyone participating in the festivities. 
Teenagers and young adults are traditionally sent into the woods around twilight, in order to gather twigs, sticks, and greenery to decorate the houses within the town and bless them with fertility and joy in the coming year. In exchange for decorating their homes, teenagers and young adults are expected to be paid in eggs, alcohol, or other edible treats, with eggs being the most traditional.
Group singing is a common practice, with people singing popular or traditional carols together at various, impromptu times. Skalds and musicians would perform for entertainment, and audience participation is encouraged. 
In regions with rivers, it is traditional to make homemade, highly decorated rafts and attempt to raft across the waters. The wreckage of many rafts can be seen for months afterward. If there is no river, floats or other crafts are paraded through the main street; given the rowdiness of the festivities, these are also typically wrecked. 
The rowdiest celebrants are typically college-age students, as Valborgnatt coincides with the end of the spring term's final exams and the transition into the summer break.

Sources:

• Williams, Victoria (21 November 2016). Celebrating Life Customs around the World. ABC-CLIO. p. 217. ISBN 9781440836596.
• Frazer, James G. (1961). The New Golden Bough. Anchor Books. p. 356.
• Galván, Javier A. (19 June 2014). They Do What? A Cultural Encyclopedia of Extraordinary and Exotic Customs from around the World. ABC-CLIO. p. 51. ISBN 9781610693424
• E.L. Rochholz (1870). Drei Gaugtinen (Three Local Goddesses)
• Wunderli, Richard M. (1992). Peasant Fires. Indiana University Press. p. 46. ISBN 9780253207517.
• Stark, Lucien (1998). Brahms's Vocal Duets and Quartets with Piano. Indiana University Press. p. 100. ISBN 9780253334022
• Melton, J. Gordon (2011). Religious Celebrations. ABC-CLIO. p. 915. ISBN 9781598842050