|Australian diver David Bardi at the "habitat" |
(-38 m) in the Pearse River resurgence.
The group returned from the remote Motueka Valley river head this week after spending a fortnight exploring the intricate underwater cave system.
Diver and explorer Craig Challen pushed the human limit, reaching 221m, breaking the 194m record he set in the river cave last January and setting an Australasian record.
The Western Australian vet said delving to a dark depth felt like "a long way from home".
The 17-hour dive saw him stop four times at underwater "habitats" which were filled with trapped air. They provided a base for divers to rest and decompress before continuing their return to the surface.
Mr Challen said diving into the uncharted cave at that depth was like "dipping your toe in the unknown".
It was the third time the six-member team had returned to explore the Pearse.
Mr Challen said the expedition was as much about exploration as endurance.
"As far as exploration goes, this is the No1 site in the world."
Team leader Adelaide's Dr Richard Harris said marker dye dropped by Nelson cavers in the Nettlebed system was seen by divers below 200m and indicated the system was more than 1000m long. However, the connection could be proved only when it was travelled and charted.
It was the third time the group had explored the system in the last three years. Mr Challen said at the end of each trip the group's consensus was that they did not want to return.
"Then after a week or so we remember the good bits. And if we don't come back someone else will."
He said the cave continued its plunge after 221m. But even with the help of tonnes of technical gear, heated suits and battery-powered underwater scooters the chances of going much deeper were diminishing.
"When you get to over 200m you are working outside human physical limits."