"Kaljakellunta", also known as “Beer Floating”, is an annual open festival originating from the Uusimaa province of Finland, where the capital city Helsinki is also located. Kaljakellunta is an event where thousands of participants float down the Kerava/Vantaa river in various kinds of inflatable dinghies and self-built rafts, whilst getting drunk on beer. That is also where its name originates from; “Kalja“ stands for beer and “Kellunta” for floating in Finnish.

The Beer Floating event has been organized annually since 1997. There were under 10 participants in the first event in 1997 but ever since the number of participants has grown every year. In 2011, around 5 000 people participated in the event. The date of the Beer Floating event has been varying but the most likely dates are considered to be either the last weekend in July or the first weekend in August.

The event has no official organizers but instead the date is decided on online social forums such as Facebook or IRC-Galleria. The Beer Floating event is also organized in Oulu, where the participants float on the Oulu River.

More Info: en.wikipedia.org