Mahe Drysdale doesn't know if he will be able to walk this morning, as he recovers from a "gruelling but fantastic" Coast to Coast on Saturday.
The 2012 Olympic gold medallist is accustomed to pain but says the 243km race was probably the toughest thing he has ever done.
The 34-year-old completed the course, which includes three cycle legs, two runs and a 67km kayak down the Waimakariri river, in 14h 8m to finish 39th overall.
"I loved being a part of it - it was incredible - but there were some pretty dark times out there," said Drysdale. "You are in constant pain for a long, long time. It is mentally very tough, probably tougher than a rowing race or the long-distance training sets we do. They can be two hours - this was another 12 hours on top and I was well out of my comfort zone."
On Saturday night Drysdale could barely walk up the stairs to his bedroom and was "shaking uncontrollably" in bed.