For some it is the elite competition, for others victory comes with completion. And for others it holds special significance.
Take Whenuapai cancer survivor Mark Blakey, who was given a grim prognosis after contracting cancer of the bladder. That was three years ago and Mark, a former runner, has already completed the Auckland marathon and, after a challenge from a workmate and his stepdaughter, is taking on the State Harbour Crossing.
"I am just a fat boy from England who works too hard and likes to push himself by doing dumb things like swimming across the harbour. It should be fun," said the 48-year-old.
Blakey is fortunate he can swim at all. His world was turned upside down when he was told by doctors that his days were numbered. Blakey never accepted that diagnosis and travelled to the United States to get innovative surgery on his bladder to ensure he wouldn't have to carry a bag around for the rest of his life. Now he can focus on other battles that are much more positive.
"Once you have picked yourself up from cancer, you can overcome any other challenge - it is all easy compared to what I have been through. I have got back into running marathons and this is another thing for me to tick off the bucket list. It is out of my comfort zone. The doctors had given up on me and thought I had little time to live, but here I am feeling fighting-fit and about to do the State Harbour Crossing."