Ice skating marathon

Ice skating marathons are long distance speed skating races which may be held on natural ice on canals, and bodies of water such as lakes and rivers. Marathon is a discipline of speed skating, which is founded in The Netherlands. 
The races concern speed skating by at least five skaters who start all together on an ice rink with a minimum length of 333.33 meters or on a track:
Most famous race is the Elfstedentocht (Eleven Cities) ice skating marathon (200 kilometers) on frozen canals in The Netherlands.
Marathon Ice Speed Skaters Erik Jan Kooiman and Carien Kleibeuker currently possess the world hour record men (43.735,94 meters) and ladies (40.569,68 meters).
See also.
KNSB Dutch Marathon Championships