One of two girls airlifted from an Outward Bound course in the Marlborough Sounds remains in hospital in a stable condition.
The two students were airlifted from the Mount Riley area, west of Blenheim, after becoming unwell on an tramping trip.
Their instructor, from the Outward Bound School in Anakiwa in the Marlborough Sounds, called police on Sunday to ask for assistance when the girls became ill.
But deteriorating weather meant the rescue helicopter was unable to reach the group until about 7am on Monday morning.
The girls - both aged 17 - from Carterton and Gisborne, were taken to Wairau Hospital in Blenheim for treatment.
One, who had abdominal pain, is in a stable condition at Wairau Hospital in Blenheim. The other student is reported to have become cold and exhausted while assisting the group.
She was also admitted to Wairau Hospital but has since been discharged.
The remaining 12 students and their three instructors walked off the mountain.