More than 20,000 revellers turned the Spanish town of Buñol red on Wednesday as La Tomatina, one of the world's most unusual festivals, returned for another year. Participants hurled around 165 tonnes of overripe tomatoes at each other over the course of just over an hour, leaving streets — and people — buried in red pulp.

Trucks loaded with tomatoes moved slowly through the packed crowd while people in the cargo beds pelted those below, who enthusiastically threw them straight back. White shirts turned pink within minutes. Residents watched from balconies, dousing participants with water, while buildings along the route had been wrapped in tarpaulins in advance to protect them from the mess. The festival's one firm rule: squash the tomato before you throw it, to reduce the risk of injury.

La Tomatina is held each year on the last Wednesday of August in Buñol, a small town in the Valencia region of eastern Spain. The tradition dates to 1945, when a street brawl during a local parade reportedly escalated into an impromptu tomato fight. What began as a spontaneous incident has since grown into a globally recognised event, drawing visitors from across the world. Roughly 40 percent of participants over the past three years have come from outside Spain, with a notable rise in Indian tourists — a trend widely attributed to the 2011 Bollywood film Zindagi Na Milegi Dobara, in which characters take part in the festival.

The festival's international appeal underscores how a local quirk can become a global cultural touchstone. For the town of Buñol, which has a population of only a few thousand, the annual influx represents a significant logistical undertaking as well as a major boost to the local economy. Organisers coordinate the delivery and distribution of vast quantities of specially sourced overripe tomatoes — this year amounting to approximately 150,000 to 165,000 kilograms — deemed unfit for eating but perfectly suited for throwing.