Question

The elfstedentocht, or 11 cities tour on ice, is held in Friesland in the north of the Netherlands at irregular gaps, though never more than once a year, and is anticipated by amateur and professional skaters alike. What determines when it is held?

Answer 1

The ice must be, and remain, at least 15 cm thick along the entire almost 200 km course
The tour is an endurance event which provides speed skating competition as well as amateur sight-seeing, and follows a route along canals, rivers and lakes visiting the eleven historic Frisian cities: Leeuwarden, Sneek, IJlst, Sloten, Stavoren, Hindeloopen, Workum, Bolsward, Harlingen, Franeker, Dokkum, then returning to Leeuwarden. It has been a tradition in the Netherlands since at least the 18th century. It takes place rarely and has happened only 15 times since the first formal event was established in 1909, the last being on 4 January 1997.