Elim Christian College pupils on the ill-fated Tongariro adventure course were ordered not to phone or text their parents to let them know they were alive.
"That was the worst thing," Tom Cozens, 15, said. "We weren't allowed to contact our parents because the parents of the dead students didn't know." With cellphones already confiscated on arrival, they had no choice but to comply.
Six pupils and a teacher, part of a group staying at the Sir Edmund Hillary Outdoor Pursuits Centre, died after flash flooding turned a gentle central North Island stream into a torrent.
Their classmates from the Auckland college endured an agonising wait while three survivors were brought back to camp - then eventually were told no more would be returning alive.
Tom said his parents were among the last to find out their child was alive, as there were two Toms in the group and it took them a while to work out which one was dead.
"People at home knew before we did," Tom said.