The Elfstedentocht (English translation: "Eleven-cities Tour") is a speed skating competition and leisure skating tour held irregularly in the province of Friesland, Netherlands.

The tour, almost 200 km in length, is conducted on frozen canals, rivers and lakes between the eleven Frisian cities: Leeuwarden, Sneek, IJlst, Sloten, Stavoren, Hindeloopen, Workum, Bolsward, Harlingen, Franeker, Dokkum and finally again Leeuwarden. The tour is not held each year, mostly because the Dutch winters do not permit skating on natural ice every year.

Adding to that, the tour currently features about 15,000 amateur skaters taking part, putting high requirements on the quality of the ice. There is a stated regulatory requirement for the race to take place that the ice must be (and remain at) a minimum thickness of 15 centimetres along the entirety of the course.

Since the Elfstedentocht is such a rare occurrence, its declaration creates excitement all over the country. The day before the race many Dutch flock to Leeuwarden to enjoy the party atmosphere that surrounds the event. The evening before the race called the "Nacht van Leeuwarden" (Night of Leeuwarden) becomes a giant city-wide street party (Frisians, who have a reputation of surliness, are said to thaw when it freezes). At the day of the race most Frisians stay home to watch the race on television.

Since 1909, the tour has been held 15 times. The last race was 1997.

http://en.wikipedia.org/wiki/Elfstedentocht
http://www.elfstedentocht.nl/ (dutch)

(this question settles "no" if no race took place by suspension)