The Elfstedentocht is a nature ice skating race between eleven Frisian cities currently organized by the Royal Association of Eleven Frisian Cities. Due to climate change, its frequency has decreased over the past decades, and it seems possible it will never happen. It was held 12 times between 1909 and 1963, and after that only in 1985, 1986, and 1997).
All correct answers resolve YES. All verfied incorrect answers resolve NO.
For a competition to qualify as an Elfstedentocht for purposes of this question, it has to be an ice skating competition on a course between all the original cities with at most 3% of the distance being travelled on something other than ice skates. The 'ice' may be artificially produced and may be partially or entirely made of substances other than water, as long as the locomotion of the sport is still that of ice skating.
If the organizing committee disbands and it seems likely (by my judgment call) that no replacement will be found, I will resolve the remainder of the questions early, re-opening them if it ever does giet oan.
(when making bets, also take the possible collapse of part of the north atlantic current into account)