The marathon swimmer completed the 2km open-water ice swim during day one of the International Ice Swimming Association (IISA) Aotearoa New Zealand National Open Water Champs in St Bathans yesterday.
Harder than it sounds, the feat involved swimming two lengths of the lake in water temperatures hovering between 2degC and 3degC.
Starting from the shore, Sherwen quickly found her rhythm, churning through the glassy water with ease and completing the first lap with energy to spare.
That changed during the second lap, where her pace slowed and she started to pause.
Under the watchful eye of medics and lifeguards tracking her form, Sherwen continued, though at times it was unsure if she would call it and be pulled from the water.
However, grit and determination were the markers of her swim, and in the last 150m, buoyed by supporters cheering from the side of the lake, she pushed through to the finish.
Sherwen completed the swim in 40min 52.85sec.
Prior to Sherwen’s swim, the scene was set with four competitors completing the 1km swim.
"That was a feat in itself for all of them to achieve that," IISA Aotearoa New Zealand chairman Roger Soulsby said.
Wei Ping Chew, of Christchurch, demonstrated "phenomenal" grit in the last 100m to finish her swim, which set the scene for Sherwen.
Sherwen successfully tackling the extreme ice mile was the highlight of the day, Soulsby said.
"Beautiful conditions — you couldn’t have programmed the clear lake, calm and the right temperature for Sue. And she’s done a lot of miles — her background is a extreme swimmer.
"Anyone able to do 2km in water under 3degC is really quite extraordinary."
Day 2 of the championships continues today.
