"As far as we know we're the first school to do it and run the whole way, it feels awesome to be a part of it."
They are doing the run as a relay, splitting the country into regions and providing an opportunity for as many student volunteers as possible to get involved.
The students were returning to Palmerston North later in the day, before returning to Whanganui in the morning for the final 200-plus kilometres.
"It's the last stop for me, then they do another leg and I might join in again in Wellington," Isaac said.
"When you've got a whole bunch of mates beside you and music in the van it's pretty easy to keep motivated."
The Palmerston North Boys' High School Te Araroa Trail Challenge is the idea of sports and cultural dean David Barwick.
He said they have been averaging 120km travelled each day and was pleased with the way the event was unfolding.
"The boys have been absolutely phenomenal and have really embraced what we're trying to do," he said.
"Going down the Whanganui River today, none of them have ever been on that road before, it's just beautiful scenery and it was quite magical."
Ronald McDonald House was chosen as the charity as many students or their family members have had access to it in some way.
An everydayhero page has been set up which people can visit to see updates and donate funds towards the cause.
So far donations on the website total a little over $9000, but that figure does not include any other funds raised and Mr Barwick said the total is closer to $20,000.
"It's been mind-blowing the response we've had. Everywhere we've gone, people have donated things to us," he said.
"Last night, we turned up in National Park and we had a banquet of food, we've been very fortunate with sponsorship."
Some more Palmerston North Boys' students depart Whanganui tomorrow just before 7am bound for the Tararua Ranges.
Their trip concludes in Wellington on Tuesday, April 17.
"All the boys who have helped are meeting at Ronald McDonald House on Tuesday and then we're running the last 5k to Island Bay as a group," Mr Barwick said.
"And then we're going to rest."