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. 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. By 11 that evening, those still skating were taken off the ice in police cars.