KEY POINTS:
A massive rescue operation is under way after three cavers became trapped near Motueka this afternoon.
Senior Sergeant Grant Andrews of Motueka police said the three were stuck in Harwood's Hole, at the top of Takaka Hill.
One of them was seriously injured at the bottom of the
hole and the others were caught on the climbing rope at different depths of the hole.
It was not believed the other two were injured, but police were concerned they had been caught on the rope for considerable time.
Emergency services were alerted to the problems about 12.40pm by a fourth climber in the party.
Mr Andrews said police did not know the extent of the injured person's injuries.
Police, search and rescue teams and cavers were preparing to rescue the three and a helicopter would be used to take the climbers to Nelson Airport, Mr Andrews said.
"This is a difficult rescue given the location and type of terrain and it is expected it will take into this evening to rescue the trio."
The identity and experience of the climbers was not yet known.
Harwood's Hole is described on travel website totaltravel.com as a massive sinkhole .
Just off the main Motueka-Takaka road, it is part of an intricate network of hidden limestone caves that runs through the hill, and starts with a 176m vertical drop down a hole more than 15m in diameter.
In December 2004, after four experienced climbers were assisted from Harwood's Hole - the third rescue in a year from the cave system - Nelson search and rescue coordinator Sherp Tucker said it was frustrating that people continually went into the hole without enough planning or experience.
Even though that group included a West Coast alpine guide and three Department of Conservation staff, he said the cavers had not had enough knowledge to complete the trip.
"People think the hardest part is the hole, but there is a technical caving system to get through as well."
The group rejected the criticism saying they had made a navigational error.
According to the national Speleological Society, police normally call in a regional search and rescue adviser for Harwood's Hole, and appoint a field controller to manage the operation, while an underground controller is in charge of the operation in the cave.
Radio communications are not possible underground, but sometimes communications can be established using a specially-made earth-return telephone, called a Michie-phone, which is connected at any point along a wire laid through the cave at the start of the rescue.
Harwood's Hole has been the site of a number of dramatic rescues, including the "Operation Long Drop" rescue on March 25, 1995, which involved the lowering of a doctor down to a Christchurch caver who had badly fractured his leg. The doctor stayed with the man administering morphine to him for 10 hours.
In January 2004, a group of five cavers, three men and two women made up of two New Zealanders, an American, a German and an Israeli, reached the bottom of the cave, but then got lost on the walk out.
The American man climbed four hours to the top of Harwood's Hole to get help.
In July 2002, rescue teams found two men fit and well after they became lost in the cave in a site known as Shorty's Terror.
- NZPA