An experienced caver believes it was irresponsible for a school caving trip in Northland to go ahead when severe weather warnings were in place.

A group of 15 Whangārei Boys’ High School students and two adults ran into trouble during bad weather at the Abbey Caves near Whangārei on Tuesday morning.

The trip to the caves was part of a year 11 outdoor education program.

It’s understood one of the students was swept away by floodwaters, prompting a six and a half hour search by emergency services.

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The search for the teenager was suspended at 5pm on Tuesday and will resume at first light on Wednesday, police said in a statement Tuesday night.

Experienced caver and qualified caving instructor Neil Silverwood​ – who is not involved in the rescue – said small cave systems, such as the Abbey Caves, act as “natural drains”.

When there is significant rainfall on the surface, caves can flood quickly.

“The smaller the cave, the faster things will change.”

Asked what it would be like inside a cave as it floods, Silverwood said the noise would be intense and it would be cold.

“You’d virtually feel the walls vibrate.”

“It [the water] would potentially rise really quickly and dramatically.”

It is recommended there be one caving instructor per 10 beginner cavers, Silverwood said. This ratio recommendation changes to 1-5 during bad weather conditions.

Silverwood said it was up to the caving instructor to check conditions are suitable.

“We have other people’s lives in our hands.”

Given the weather warnings that were in place, he believed the trip should have been cancelled.

Chairperson of the school’s board, Andrew Carvell, said he was notified of the incident by the school’s principal on Tuesday morning.

“It’s a very traumatic situation for [those] involved. We’re hoping for a positive outcome,” Carvell told Stuff.

Carvell said the board was working with the school to ensure support was provided to students and others affected.

“At the moment it’s a tragic situation and we need to deal with what’s in front of us. We anticipate there are going to be questions. I think those questions are reasonable questions to ask.”

Carvell said he did not know specific details about the events that had unfolded.

“Our thoughts are with the family.”

On Monday morning, MetService issued a severe thunderstorm watch for Northland between 10am-5pm on Tuesday.

“Some of these thunderstorms may become severe, producing localised torrential rain in excess of 40mm per hour and a slight chance of a damaging tornado.”

“Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.”

In a post on social media, Whangārei Boys’ High School principal Karen Gilbert-Smith​ said the incident was “hugely upsetting”.

The post was met with criticism from people who believed the incident – which was reported to emergency services at 10.26am – was avoidable.

“I’m blown away the school allowed this to happen, we were all aware the weather was coming. Why would you allow this trip to continue?” said one comment.

Gilbert-Smith said her thoughts and aroha were with the missing young person’s whānau.

“In time we will seek to understand how this situation occurred, but for now I ask that we stay united as a WBHS community and provide support where required.”

According to the Whangārei District Council website, the Abbey Caves are prone to flash flooding. It suggests people check the weather forecast before visiting.

There are three caves at the site – the Organ, Middle and Ivy caves.

“Only experienced cavers should enter the underground caves, as there are risks from rapidly rising water and roof falls.”