Because it is always dark underground, one of the most important pieces of caving gear is a light source. Traditionally the main source was a carbide light generator. Calcium carbide was mixed with water to produce acetylene gas. At first the generators were miners' lamps, and the carbide was carried in the cap lamp. These were then replaced by lamps with carbide carried on a waist belt, which were still in widespread use in the 2000s. Increasingly though, carbide lamps are being replaced by headlamps with light-emitting diodes (LEDs). Torches are taken as a back-up.
Cavers wear helmets, polypropylene thermal underwear, overalls, and sturdy boots. They use an abseiling harness in caves with vertical sections, where caving is similar to rock climbing.
Safety is the caver’s top priority. Being underground, often many hours’ walk from the surface, means that some injuries can become a very real threat to life. Badly injured cavers must be carried out on a stretcher. There are now specialist search and rescue teams, but a vertical section or a tight squeeze can prove a major obstacle.
Cavers have strict safety practices. They always carry three sources of light and a map of the cave. The sport is a team activity and the emphasis is on cooperation. Even so, mishaps do occur – in New Zealand at least four people have died in caving accidents. In 1998 one of the country’s most experienced cavers, Kieran McKay, broke his jaw after falling deep within Bulmer Cavern on Mt Owen. Luckily Bulmer has few crawls and no tight squeezes. A major rescue operation swung into action, involving 80 cavers from around the country. McKay walked out of the final section on his own.
Exploration: maps and dyes
Enthusiasts use topographical maps when looking for new caves. Once these are found, new underground maps are drawn, detailing the structure of caves.
These maps are essential for return trips and those new to caves. They are published as the New Zealand cave atlas, with North Island and South Island editions. As caves are dangerous places for the inexperienced, entrances are not marked on topographical maps.
Dye tests are also valuable. A special green dye called fluorescein is placed in subterranean streams, and suspected springs or resurgences are monitored for traces of the dye. If it shows, this indicates that the stream feeds the spring, helping cavers to link caves with downstream drainages.
Two of the great challenges are to join two known cave systems, and to find more entrances. Sometimes a wind blowing out of the cave mouth is a sign of other entrances.
Trip by trip, tunnels and shafts are followed and surveyed – some with dead ends, others leading to huge caverns and further links.
Wacky cave names include the Hinkle-Horn Honking Holes and Goodbye Yellow Brick Road. Both are in Nettlebed Cave on Mt Arthur. Deep within nearby Bulmer Cavern, on Mt Owen, are Wellington on a Bad Day and Where the Wild Things Are.
The New Zealand Speleological Society first published the New Zealand Speleological Bulletin in 1952. It also publishes a quarterly newsletter, Tomo Times. Regional club newsletters (some with droll titles such as Wellington’s Sumpthink and Canterbury’s Cavity) feature upcoming trips and new discoveries. Delving deeper: half a century of cave discovery in New Zealand (2003), by Moira Lipyeat and Les Wright, is the definitive history.
Many clubs have websites featuring their latest trip lists and other news.
Acknowledgements to the New Zealand Speleological Society