For over ten years, what U.S. city has held the "Tube To Work Day" event?

In the spirit of finding alternative transportation to work, hundreds of people braved the cold waters of Boulder Creek, Colorado on the Tube to Work Day, donning everything from business attire to outlandish costumes. It is considered one of Colorado’s silliest traditions for allowing employers and workers to appreciate their city as a work site.

The concept is simple: instead of riding a bike, taking a bus or carpooling to work why not get from point A to point B on a tube? Many of the tubers braved the rapids near downtown Boulder wearing ties and biking helmets. They look just like many of the other commuters who go to work during rush hour. The tradition started in 2008 when two friends went tubing; it has now been done every year since then.

Also to make the experience more enjoyable, a free breakfast and coffee is always offered to tubers on the shore of the creek near Broadway Boulevard.