"The kids are the main ones that are malnourished or not looked after. I've got a really close family and we identified with giving every child an equal chance in life.
"The big starting point is making sure the children aren't malnourished; we want them to have a good meal, lots of support, education and a chance at a good life. It's something I have a real affinity with."
Nock is hoping to raise $10,000 to donate to ChildFund New Zealand which will go towards the fight to end child poverty.
"We're about $300 off our $10,000 target which is absolutely fantastic. If I come up hearing claps, it'll be all worthwhile," he said.
"ChildFund's goal is to rid child poverty worldwide. That's not just in Africa, it's here in New Zealand and others. They don't look at anything else but addressing and ending child poverty worldwide.
"The money we raise from the swim won't go towards infrastructure. It's aimed at specifically supporting the significant famine in Africa. There is 1.4 million children at risk of dying from that so it's a very small drop in the ocean but more importantly it gets the ChildFund name out there.
"Hopefully it gets people to think about instead of having a beer at $7 or whatever it is, it can go towards this. It's a small drop in the ocean for us but can make the world of difference in need."
Nock said his training for the swim had been going well, but a simple misunderstanding has made the task a bit more daunting.
""I thought my preparations were going well when I was training for a 2.5km swim but then I found out it was actually 3.3km so I'm trying to get the extra 800m done. But I am confident we will get there.
"Training has been cutting back on food and drink and losing weight. Also getting down to the Kawakawa pool every morning and getting lap training in has been a big part of it.
"It will be my first time in the ocean during the preparations on race day. I haven't practised in the ocean at all while training. I have swum in oceans but not this one.
"Time wise, I've made the pledge to do the swim in under an hour or people don't have to put their hands in their pockets. Most people have waived that though since they found out about the extra distance.
"I'm actually scared to look at the weather forecasts. I looked at the ocean today and wish I hadn't. I'm told if the wind's behind you, you can semi surf across. If it's a westerly wind and flat water, I'll be happy."
More than 800 swimmers are expected for the event.
For confident swimmers, there is the 3.3km I'm Going Long event from Russell to Paihia, while those getting used to open water swimming can compete in the 300m Give it a Go swim off Paihia Beach.
For youngsters, there's the 200m Banana Boat OceanKids swim for ages 7 to 12.