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2014 Pearse Resurgence Expedition

January 2014 saw the Wetmules return to the Pearse Resurgence and Nettlebed Cave near Nelson in New Zealand for further exploration. As always, local Nelson Speleological Group members “Oz” Paterson and Deb Cade assisted them, as well as Andrew Smith who provided dry caving support. This year’s dive team comprised Dave Bardi (VSA), Craig Challen (CEGWA), Richard “Harry” Harris (CEGSA), Dave Hurst (CDAA), Luke Nelson (CEGWA), Ken Smith (CEGSA) and Sandy Varin (VSA).

                                                          L-R Harry, Dave B, Ken, Dave H, Luke, Sandy and Craig.

This year’s trip had three goals:

·      To attempt a dive in the sumps of Nettlebed Cave from where earlier dye tracing had shown a good

     connection to the Pearse River,

·      To further push the deep passage of the Pearse Resurgence itself,

·      To map as much of the deep passage as possible using the new electronic Cave Logger (C-Logger).

Dave and Sandy spent much of the trip dealing with the hardships of carrying dive gear into the Nettlebed sumps, with the assistance and guidance of Andrew Smith. In 2012 the Wetmules performed a fluorescein dye trace from the “Spillway”, seeing a strong positive result in the Pearse River in less than 36hrs.  The goal: to see if we could start working from the Nettlebed end with divers to avoid going much deeper in the main resurgence.  Information from Oz Patterson suggested that the sumps in an area called Sewers Canal were probably downstream from the Spillway, and that being more accessible than the Spillway they would make a good place to dive. The obstacle known as the Hinkle Horn Honking Holes would still make for some interesting caving to get dive gear to the sumps!

                                                      Dave, Andrew Smith and Sandy heading off for a day's caving.

Over a period of 5 days solid caving, Dave and Sandy performed two sets of dives in the two obvious sumps. The sump on the right side was silty and did not seem to go. The left hand sump held more promise and between them they laid 150m of line through shallow sumps, which regularly became rift chambers and streamway requiring as much crawling and walking as swimming. The left sump continues in at least two directions and still holds promise as one section is heading approximately 030 degrees (towards the Pearse). Surveying with knotted line, compass and depth gauge was performed but more work remains to be done here.

                                                                         Sandy, what did they do to you?!

Meanwhile back at the Pearse, the setup dives for a deep push revealed the usual challenges and obstacles. Malfunctioning electronics on one of the habitat micro-rebreathers, heating battery issues and some drysuit floods were bad for the team’s confidence and we started to think about shifting our goals towards helping Dave and Sandy, and doing more shallow mapping and exploration in the Pearse. However a shallower exploratory dive to 170m by Harry and Dave Hurst (amazing effort on Dave’s first trip to this cave, and well done on mastering the twin Megalodon rebreather!), revealed a new passage at the end of the M40 just past Stanton’s Hole (the previous entry point to the deep system). Harry and Dave explored and videoed another 30m of tunnel past Stanton’s Hole, ending in another large and beckoning floor hole.  Ken’s C-Logger successfully documented the short new section that was named the “Pig’s Tail” after its corkscrew shape.

                                            The C-Logger mounted on the Genesis scooter raring to go!

Two days later, Craig and Harry set off as a buddy pair to see if the new hole would drop down into the deep tunnel (Wetmules Way) discovered in 2012 by Harry (207m) and Craig (221m depth). Both divers utilized dual rebreather systems. Armed with Harry’s new dual 13000 lumen video lights mounted on one scooter (thanks Damien Siviero!), and the logger on the second scooter; the pair made good time down to the new passage where a reel was deployed and the exploration began. Initially the passage dropped swiftly to nearly 180m then continued less steeply for the next 50m of passage. A final drop into a large void where Craig tied off the empty 75m reel, while Harry tried to glimpse the floor below. There was an impression of a tunnel heading across the bottom of the hole with the floor estimated at over 220m. The very loud implosion of an external buoyancy cylinder on Harry’s scooter gave both divers such a fright that a speedy exit from the maximum depth of 217m was made!

                                                            Craig and Harry prep for a deep dive.

Subsequent analysis of the logger data shows that the tunnel has dropped below the Wetmules Way and is quite separate, although it must be very likely to rejoin further into the cave. The tunnel is easier to move through than the previous route and could now be considered the main conduit. This second approach to the cave gave rise to the name “Second Breakfast” (as favoured by Hobbits!). Sadly the video from two different cameras did not come out…we suspect operator error!

                                                                    Empty reel = success! 

The trip finished with the usual cleanup dives and a celebratory trimix dive by Ken to 130m using up the leftover gas…a new PB and an excellent achievement by the team boffin. Luke worked tirelessly throughout both in and out of the water supporting deep dives, repairing anything left laying still for more than a few seconds and keeping the show on track. Sandy and Dave ran the usual tight ship in the catering department whilst Harris and Challen managed to escape all domestic chores wherever possible. Dave Hurst confirmed his skill as a superior porridge chef.  John Dalla-Zuanna was greatly missed on this trip but his support and gear were greatly appreciated.

                                                                    Gear in, gear out...easy come, easy go!

The Wetmules would like to thank the New Zealand caving community especially of course Oz, Deb and Andrew for their endless help and hospitality. Thanks to Syd Deaker from Action Helicopters, Malcolm from BOC Nelson, O’Three Drysuits. Golem Gear, ISC Megalodon, rEVO Rebreathers and our new favourite product – the Scurion Dive light. Still happy at 217m!

                                        The Blue Duck...an old friend of the Wetmules and a good luck omen for the team!

Latest map from the Pearse based on information gained from the C-Logger.


Inside Nettlebed Cave