Haro Wine Festival is a summer festival in the town of Haro in the La Rioja region of Northern Spain. It features a Batalla de Vino (Battle of Wine) and youth bullfights.
The best time to visit Haro is for the major event of the year: The Batalla Del Vino. On Saint Peters Day (El dia de San Pedro), which is June 29th every year, the population of 11,500 in the central Rioja town of Haro swells to almost double that, and early on the morning of the 29th it descends into outright “Wine Warfare” in the chaotic and spectacular “Battle of the Wine”.
Walking through the streets is like a ribena berry overdose.
+ More information > Wikipedia • Wikivoyage

A mass is then celebrated at the Hermitage of San Felices de Bilibio. After the mass, the Battle of Wine commences. The participants toss wine on each other until everyone is completely soaked. This is a super fun event and tourist friendly. At noon, the festival continues at the Plaza de la Paz (map).
Since the early 19th century Haro has established a worldwide reputation for being the most important wine town in the Rioja wine region and remains so today even though the number of Bodegas in the region have multiplied 8 times to 574 during the past 50 years (1970 to 2020). The key focus of this reputation is at the Barrio Estación where 7 of the best Rioja Bodegas are located – namely Bodegas Bilbainas (founded 1859).
Rioja wine is made from grapes grown in the La Rioja and Navarre, and the Basque province of Álava. About 90% of the cultivation is of red grapes, the remainder being white grapes. Rioja is subdivided into three zones: Rioja Alta, Rioja Oriental and Rioja Alavesa. Many wines have traditionally blended fruit from all three regions, though there is a slow growth in single-zone wines.

HOW TO GET TO THE WINE FIGHT (wine-fight.com)
+ Get to Haro (haroturismo.org) • Getting around Spain (spain.info)
Always check whether the bus or the train is more convenient. The least expensive way to get around most parts of Spain is by bus.
BUS > Virtually all companies operating Intercity buses in France including Ouibus and even German players Flixbus offer buses to/from Spanish destinations. ALSA • Grupo Avanza • Socibus and Secorbus. You can also see what is all available on Movelia.es.
RAIL > The main train operator is RENFE, including AVE (Spanish high speed train) or Talgo intercity services. (*Rail travel in Europe)
AIRPORTS > Information about Spanish airports > aena.es.
WATERWAYS > Baleària • Grimaldi Lines • Trasmediterranea. Spain’s main sea connections (spain.info)