BOULDER, Colo. (AP) — Some people in Colorado stayed cool on their commutes by tubing down a snow-fed creek.

The Daily Camera reports that 1,000 people participated in the 12th annual Tube to Work Day in Boulder on Friday, one of the hottest days of the year so far.

The event is aimed at promoting alternative transportation and celebrating the city’s quirkiness. Organizers bill it as the “world’s greatest traffic jam.”

Television helicopter footage showed people going through mild rapids as they made their way down Boulder Creek in tubes, including some dressed in suits. People gathered on bridges over the creek to watch.

The event was delayed this year until the water subsided to safe levels following a winter of plentiful snow in the mountains.