He stops short of labelling it a mid-life crisis, but Craig Stephenson admits he was looking for a new challenge in his life.
Not one to do things by halves, the Taupo father of four has set himself the goal of swimming the 320km length of the Waikato River from Taupo to Port Waikato in March.
Stephenson says the idea first came to him about a year ago and he mulled it over for several months. At first he didn't think it was the sort of thing a working, family man could do.
``I thought that's the sort of thing that Steve Gurney or Richard Ussher would be doing, but then I read Kevin Biggar's book, The Oarsome Adventures of a Fat Boy Rower, about how he rowed across the Atlantic Ocean and he was a nobody with no athletic prowess . . .and it kind of got through my head that you don't have to be like Superman to do these things.''
He was also inspired by Little Britain actor David Walliams' swim down the River Thames in England - and thought the Waikato would be much nicer.
``Then it was just kind of one of those moments when I thought, why not? Let's do it.''
But Stephenson `s mission is much more than just an epic swim. He's also concerned about the river's health and access to clean water generally. He's employed as a project manager at Contact Energy, which has been working hard to reduce its discharges into the water but he realised that he didn't know much about the river's health downstream.
On a family trip to South Africa earlier this year, he realised that safe drinking water is an issue for many people, particularly in the Third World. So he decided to seek donations for the swim, to be donated to Unicef, which has a programme to provide clean drinking water for children, and he's aiming for $10,000.
Stephenson plans to leave from Taupo on March 11 and hopes to swim the length of the river in 10 days, although there are some bits he'll have to walk around - including Huka Falls and the hydroelectric dams. He says at that time of the year the river flows will be relatively low and he can't rely on any help from the current, which is often non-existent.
``You've got the big long hydro lakes in the upper reaches and it'll be like swimming from here to the other end of Lake Taupo.''
He also plans to swim alone for much of the way, towing a small bag with essential supplies and without a support boat or kayaker, although he'll use one on busy stretches of water such as Lake Karapiro. He'll meet up with his support crew at the end of each day's swimming and his family will join him on weekends.
When it comes to training, Stephenson has been working on improving his core strength and mixing in aerobic activities and now that the weather's warmed up, he's doing his swim training in Lake Taupo. Like many in the district, Stephenson has a special feeling for Lake Taupo and the Waikato River and he wants other people to appreciate the river and its water more than they do.
``If people can start thinking instead of just driving past the river, think what's going on with that piece of the environment, what can be done to make it better so that we can enjoy it the whole way down.''
The Waikato River passes several industrial sites, runs through dairy farming country and through a major city and becomes more polluted the closer it gets to the coast, but Stephenson says although the water quality will be an issue, he hopes to avoid becoming sick.
He says taking on the challenge was partly a mid-life crisis.
``I was looking for something to do, something hard. Life's pretty soft most of the time, we've got it pretty easy in New Zealand so I thought let's do something difficult. So hopefully it's going to be that hard, but not impossible.''
Stephenson's mission is the second known attempt to swim the Waikato River. Melbourne-based New Zealander Paul Percy completed a similar swim in 2003.
Support Stephenson by going to unicefchampions.org.nz/cause/waiswim13. He plans to keep a blog during his swim.