If you combined the endurance demands of the New York Marathon with the grueling climate conditions of the Alaskan Iditarod, you'd get a sense of the Dutch ice-skating race called the Eleven Cities Tour.

Known as the Elfstedentocht in Dutch, the one-day tour is an obsession for its 16,000 participants and the millions more who follow it worldwide. The event is held in The Netherland's northern province of Friesland but only in those years when the ice freezes over the 124-mile track of lakes and canals that makes up the route. The last tour took place January 4, 1997.

The fabled marathon was officially organized as a contest nearly 90 years ago by the Friesian Skating Association though its roots go back generations before that. This century, the race has taken place just 15 times; yet, it's become the biggest phenomenon in Dutch sports.

During a cold snap that made the tour possible one year, the white caps of the North Sea froze over. In 1929, winner Karst Leemburg finished in conditions so severe a frostbitten toe had to be amputated.

Because the competition hinges on weather conditions, lead-time is always short and the preparations furious. Wind chill, skating surfaces and ice thickness determine if and how the tour is run. Experts sometimes perform ice transplants to close holes in the route.

The 1997 race was organized with less than two days' notice thanks to a Russian cold front that left the country in a deep freeze. Despite nearly impossible time constraints, a virtual army of organizers and volunteers pulled the race off and, with it, one of the greatest tests of athleticism. The tour started before sunrise forcing skaters to navigate their first three hours by the light of spectator torches and farmers' tractor lamps. Some speed skaters wore headlamps. Henk Angenent, a farmer, won in 6 hours, 49 minutes and 18 seconds. By 11 that evening, those still skating were taken off the ice in police cars.

The tour always starts and ends in the Friesland capital of Leeuwarden and travels through the cities of Sneek, IJlst, Sloten, Stavoren, Hindeloopen, Workum, Bolsward, Harlingen, Franeker and Dokkum.

When the next race will be held is anybody's guess. And it's exactly that unpredictability that makes the Eleven Cities Tour so highly anticipated. One caveat for foreigners: Racers must be members of the Elfstedentocht Union, an organization whose membership of 16,000 was capped over a decade ago. That leaves anyone except a Nederlander with little chance to participate.

The Friesche Elf Steden" Association website