The 18-year-old was at Matapouri Bay in Northland on Saturday with his girlfriend when another swimmer got into trouble in the water.
Seconds later Mr Macpherson was braving big swells and a turning tide to rescue the man.
"People started screaming that he was in the water and my girlfriend was yelling that he was getting swept out. He was trying to get back to the rocks where he had come from, but he was just wasting energy ..."
Mr Macpherson has had no surf lifesaving training, but knew instinctively what to do.
"I'm not really a water person, I like the land much more than the ocean," he told the Herald.
"I could see ... he was panicking and wasting a lot of energy and I thought if I was out there with him he might calm down."
The man had been swept off rocks and Mr Macpherson made his way to the same outcrop.
"His friend was standing on the rocks looking like he was about to dive in, but he didn't look like he could do it so I jumped in ... I didn't want to stand there and watch someone die in front of me.
"I got to the guy and told him to try and swim further out to sea to get to calmer water, and then we would re-evaluate and come back in.
"We were pretty much having a good old conversation out there about where we come from and what we were up to. I was just keeping him calm and talking about his life ... Then he started to calm down."
The crashing waves and turning tide meant the pair did not get far. Eventually, a wave pushed the stricken man back on to the rocks.
Mr Macpherson was not as fortunate and could not get on to the rock.
"He got pretty badly cut up as he got on to the rocks. I tried to do the same thing but I got pulled under. The water was too strong to get where he was so I had to swim back out to sea and carry on around the rock."
It took 30 exhausting minutes for Mr Macpherson to get back to shore.
"At one point I couldn't move at all. The moving tide was just keeping me in the same place ... I thought I was going to die a couple of times ... I'm happy it worked out.
"I finally made it to the beach at the exact same time the helicopter turned up. It dropped down and picked him up. When I got on to the beach I just collapsed ... They reckoned I had hypothermia and I went to hospital. But I'm fine now, I'm really good."
Mr Macpherson has been told by many who have heard his story that he is a hero. But he doesn't think so.
"Anyone in my position would have done the same thing. I wasn't going to regret not doing anything," he said.
"I didn't want to read in the newspaper about him being dead."
Mr Macpherson does not know the name of the man he rescued, just that he was from nearby Tutukaka. The man's friend and partner thanked Mr Macpherson for helping when they saw him at Whangarei Hospital.
He said the incident was a timely reminder for swimmers to take notice of the conditions.
Anna Leask of the New Zealand Herald
