▁ 2 0 0 4 , ▁and ▁eventually ▁introduced ▁at ▁the ▁Olympics ▁in ▁ 2 0 0 6 . ▁ ▁Mar athon ▁▁ ▁Sk aters ▁sk ate ▁in ▁a ▁large ▁group , ▁and ▁they ▁sk ate ▁long ▁distances . ▁When ▁conducted ▁at ▁an ▁ice ▁r ink ▁o val , ▁the ▁distance ▁is ▁usually ▁around ▁ 4 0   km , ▁a kin ▁to ▁the ▁traditional ▁mar athon ▁in ▁running . ▁When ▁sk ated ▁out do ors ▁on ▁natural ▁ice , ▁the ▁distances ▁can ▁be ▁as ▁long ▁as ▁ 2 0 0   km . ▁An ▁example ▁of ▁this ▁is ▁the ▁famous ▁El f sted ento cht ▁( E le ven ▁cities ▁tour ), ▁which ▁is ▁irregular ly ▁held ▁in ▁the ▁Netherlands . ▁Altern ative ▁versions ▁of ▁this ▁famous ▁event ▁are ▁sometimes ▁held ▁abroad , ▁e . g ., ▁in ▁Finland ▁and ▁Canada . ▁ ▁In ▁cold ▁winter s ▁in ▁the ▁Netherlands , ▁a ▁" National ▁championship " ▁sk ating ▁mar athon ▁on ▁natural ▁ice ▁is ▁organized ▁if ▁it ▁meets ▁the ▁minimum ▁requirement ▁of ▁ 1 2 - cent imet re ▁thick ness . ▁For ▁the ▁first ▁time ▁in ▁ 1 3 ▁years , ▁a ▁Dutch ▁championship ▁ice - sk ating ▁mar athon ▁on ▁natural ▁ice ▁was ▁held ▁in ▁January ▁ 2 0 0 9 , ▁in ▁the ▁O ost va ard ers pl assen ▁wet land ▁near ▁L el yst ad ▁in ▁the ▁province ▁of ▁Fle vol and , ▁an ▁area ▁of ▁land ▁rec laimed ▁in ▁the ▁ 1 9 6 0 s