"It was incredible. It was beautiful. It was the way New Zealand was 1000 years ago," he said.
He also loved Tongariro National Park, and likes the variety of the trail in general.
"You never get bored. You can be in deep forest and pop out and things completely change on you in an instant."
The most dangerous part has been walking SH1 to get through Auckland. And he's finding the North Island section is more about "getting to know the country and people". He expects a deep wilderness experience in the South Island.
Mr Swanson and Ms Horns had just hitchhiked to Taranaki and climbed to the summit of Mount Taranaki on a clear day. They may skip the next section of the trail because it involves a lot of road walking.
"We'll probably have coffee in the morning and discuss it. That's usually the way we make decisions. We try not to plan ahead too much. The adventure can come to you if you do it like that," he said.
Rain will be no problem for the two, unless there is flooding.
"We don't let rain deter us from forward progress."