The group from Elim Christian College in Auckland was swept away during an outdoor adventure course at the Sir Edmund Hillary Outdoor Pursuits Centre (OPC) at Turangi in April 2008.
The week-long inquest will start in the Coroner's Court in Auckland. Elim College principal Murray Burton said it would be a testing emotional time for families and the college.
"The majority of them (families and friends) know that it has to happen, they know they have to be there but they are not exactly looking forward to it.
Mr Burton said the families and the school were "not holding their breath" that answers might come from the inquest.
"Of course they are going to continue to hear things that are very hard to hear but are necessary to hear," Mr Burton said.
He said one of the parents told him several days ago it had not got any easier since April 15, 2008 when the tragedy shook the country.
"They are all doing a remarkable job but hearing what could have been and perhaps what shouldn't have been is very hard for them."
No criminal charges were laid over the incident but the OPC was last year ordered to pay $480,000 in fines and reparation after admitting two charges laid by the Department of Labour under the Health and Safety in Employment Act.
The Department of Labour said the OPC should have known from the heavy rain that the group should never have entered the gorge, even though the water levels were not high when they entered.
It also said the OPC should have either subscribed to the Met Service's weather warning service, or kept an eye on its website for weather warnings on the day of the tragedy. By doing so they would have picked up three severe weather warnings the day of the tragedy.
Hastings coroner Christopher Devonport is holding the inquest to find out what caused the deaths.
