WEISSENSEE, Austria — A thousand Dutch skaters congregated before dawn on the frozen surface of the Weissensee, the long, slender lake that gives this small Austrian mountain town its name. The sky was dark, and the headlamps of the shivering skaters cast a spiritual glow onto the charcoal ice. They had been warned not to remove their goggles, lest their eyeballs frost over in the wind.

The conditions, by any reasonable standard, were brutal. But the skaters were in heaven.

“The most beautiful thing in life is skating on a floor of black ice, in the cold, hearing the sounds of ice skating in nature,” said Wim Wiltenburg, 53, a banker visiting from Tilburg. “It’s better than sex.”

Speedskating on natural ice is a beloved Dutch national pastime. The tradition is alive and well — just not necessarily in the Netherlands, where climate change now yields winters too warm for the waterways to freeze over with any consistency.