The Cumulative Cold Index

The Cumulative Cold Index

Courtesy of WOWSA, Huntington Beach, California.

Ger Kennedy, one of the most prolific ice swimmers in the world and the only male to complete the Ice Sevens, achieved another cold water swimming milestone: swimming 10 km in water under 10°C (50°F) in a solo point-to-point 10 km marathon swim from Sandycove Harbour to Bray Harbour.

The sub-10°C 10 km challenge brings to mind the Cumulative Cold Index, an extremely tough cold water swimming scale that may be outside the bounds of what is humanly possible. Steven Munatones says, “I say that now, but then again, the ice swimming and marathon swimming community always accepts all kinds of mind-blowing challenges – and then learns how to meet the challenge and exceed them over time.”

Cumulative Cold Index

  • sub-10°C water for a 10 km swim
  • sub-9°C water for a 9 km swim
  • sub-8°C water for a 8 km swim
  • sub-7°C water for a 7 km swim
  • sub-6°C water for a 6 km swim
  • sub-5°C water for a 5 km swim
  • sub-4°C water for a 4 km swim
  • sub-3°C water for a 3 km swim
  • sub-2°C water for a 2 km swim
  • sub-1°C water for a 1 km swim

Munatones recalled, “In addition to Kennedy’s sub-10°C 10 km swim, there have been others who have managed a 10 km distance within a longer marathon swim or channel crossing. There have been others who have completed sub-1°C 1 km swims, named the Zero Ice Milers:

But I wonder where the bounds of impossibility lie?” pondered Munatones. “At some point, the distance and the cold get too much. At least I would think. These Cumulative Cold Index swims seem particularly tough:

  • sub-6°C water for a 6 km swim
  • sub-5°C water for a 5 km swim
  • sub-4°C water for a 4 km swim
  • sub-3°C water for a 3 km swim
  • sub-2°C water for a 2 km swim

But swimmers like Henri Kaarma (2.39 km in 0.0°C water), and Kaarma, Aleksandr Brylin, and Andrey Sychyovv have already swum 2.2 km in 0.3°C water. So who knows where the true potential lies for ice swimmers?”

Ram Barkai, founder of the International Ice Swimming Association, believes the hardest distance would be a 5 km swim in sub-5°C water.

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