''It was incredible. We all started crying ... it was a huge relief to see he was still in there. He didn't open his eyes, he didn't speak but he could hear a command and react.''
The joy was shortlived as he started choking on the tubes in his mouth and his blood pressure began to spike.
''They had to put him back under ... it was pretty rough.''
He was unsedated again yesterday morning but was unresponsive.
The family were ''staying optimistic'' and knew a recovery was often ''one step forward and two steps backwards''.
The visit to New Zealand was the first for every member of the family.
Gendron and his partner Huyen Tran Thi Thanh were passengers on the cruise ship Celebrity Solstice.
They were with a large group of Quebec residents, who had booked the cruise through Gendron's travel agency Voyages Gendron, one of the largest agencies in Quebec.
''He decided to join with a couple of friends at the last minute.''
Chinese campervan driver Wei Zhang, 34, has been charged with careless driving causing injury.
The case was called before a registrar at Dunedin District Court earlier this week and was adjourned until Tuesday.
Marc said one of the siblings would attend the court case, while the other two remained at their father's side in hospital.
The children would remain in Dunedin for as long as their father was in the city.
''We owe this guy everything. If there is anything we can do for him, we want to be here.''
They were sure their father would fight to get better because he was ''stubborn as hell''.
Despite Gendron's father dying when he was 4 and his mother being on welfare, he started to build his travel agency at the age of 14.
''He built this big thing from nothing. If he gets the chance, he is going to fight. Sometimes I worry there is too much damage but if there is anyone who can do it, it's him.''