After two days laid up with an injured back in one of New Zealand's deepest cave systems, Chris Stephenson says a return to spelunking would happen "sooner rather than later."

Aided by a few painkillers and a good nights rest, the 35-year-old science teacher was back at work on Wednesday morning.

"I've got parent-teacher interviews today so I sort of feel an obligation to be there,"  he said. 

A caver with more than 10 years' experience, the lure of exploring Nelson's deepest rock passages had brought Stephenson to Golden Bay from Norway five years ago. 

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He was supervising a five-strong group from Golden Bay High School through the Nettlebed Cave over Queen's Birthday Weekend when a seemingly innocuous task turned the trip on its head. 

The group had navigated the cave on Saturday before reaching Salvation Hall base camp, a ready-made lodging 500m below the Arthur Range which was established by the cave's first explorers in the early 1970s.

"I've been in there a couple of times previously ... it's a well-known and well-worn route for teaching kids and up-and-coming cavers how to live underground – you've got sleeping bags and mats stored in a dry spot."

Braden Fastier/Stuff

Bending over backwards is nothing new to caver Chris Stephenson, but it was his back that caused all the problems.

On the second day of the three day trip, Stephenson got up to attend to a bucket collecting water when he felt a crippling pain in his back.

"I bent over to fill up the billy and I guess I bent over a bit further to avoid the drip and that was enough to do it.

"I spent about 15 minutes trying to pretend nothing had happened then I said to the other teacher 'I think I've got an issue.'"

The other teacher - also experienced in outdoor education - endorsed the idea for the whole party to stay put and wait for help.

"We kind of tossed up whether it was a good idea to send one of the students and the other teacher out to raise the alarm but it just seemed like we were weakening the group and exposing them to unnecessary risks."

"There's a bit of complex rope work, tight squeezes and ducts where the water comes up almost to the ceiling of the cave on the way in."

Having missed their 8pm cut-off for arriving home on Monday night, parents and school staff notified police and a search party was dispatched to the Pearse Valley. 

Inside the cave, the students drew up a snakes and ladders board on the inside of a crackers box to pass the time.

Stephenson said while the pain had set in, there was never any hint of panic among the five patient cavers.  

"It's something we always planned for if the instructor gets incapacitated, and so I guess when the need arose we had that plan right in front of us."

No stranger to the twists and turns of the Nettlebed cave system, Kieran McKay was among those who helped bring the Golden Bay High School caving group out on Tuesday morning.

Rescuers entered the cave system about 1am on Monday. They arrived at Salvation Hall about 3am. 

The route to the surface included wading through waist deep water and navigating very narrow passages. 

Stephenson said the biggest obstacle was at a tricky series of squeezes near the cave entrance known as the Hinkle Horn Honking Holes.

"Around there you get really wet because the cave closes down to a really small size - the wind rips through there and you get hypothermia really quickly."

The trip back out of the cave which would usually take two hours, took the group five hours and they were back outside around 8am on Tuesday. 

Stephenson recognised the effort and support of the response teams and the school in getting the group out safely.

"There were quite a few people who'd spent the whole night pre-planning and not knowing what they were coming up against.

"Also, there's a lot of parents who I know didn't sleep at all and staff who'd stayed up too, I'm really grateful to all those people who did what had to be done in the situation but gave quite a lot in the process."

 - Stuff