A teenager was just minutes from finishing a 12-hour adventure race when she crashed off her mountain bike.

Event director David Tait said it was worst injury he had seen in his 11 years of adventure racing.

The Taradale High School student suffered head, neck and back injuries while competing in the GO-4-12 Youth Adventure Race, as part of the New Zealand Secondary School Adventure Racing Championships.

With no road access to the track, the Nelson Marlborough Rescue Helicopter airlifted the 18-year-old to hospital.

Advertisement

Rescue helicopter pilot Tim Douglas-Clifford said he and his team arrived at the Kaiteriteri Mountain Bike Park about 7.45pm after the teen took a "hard fall".

"She was a bit knocked around, the fall resulted in head, neck and back injuries."

She was coming down an intermediate-level track named Jaws.

Mr Douglas-Clifford said the helicopter crew had picked up a few mountain bikers who had come off on that track.

Mr Tait said the incident occurred right at the end of the day, just before dark. The race consists of mountain biking, running and navigation, and rafting/kayaking.

She was "minutes from the finish line", Mr Tait said.

"It's just one of those things unfortunately."

He said it was always nerve-racking when a young person hurt themselves, but these weren't "couch kids" and they knew the inherent risks of adventure racing.

"They get out and put themselves on the line, with adventure comes risk."

Mr Tait commended those around the teen at the time of the accident.

"The young people around her did a fantastic job assisting."

He wasn't sure where the Taradale team were positioned at the time but they were an "extremely good racing crew".