Riwaka Resurgence Cave Diving
Climbing bus sized boulders in a cave beneath the Earthâs surface wearing a tight fitting rubber suit is not an experience that is had on every dive.
Most divers in New Zealand consider diving to be solely a marine pastime. Few take time to explore alternative environments. However, there are many experiences to be had in freshwater environments such as rivers, lakes, springs, dams and caves. While there is limited wildlife to encounter, the sensations generated merely by being somewhere totally different are certainly enough to make the experience both exciting and rewarding. One such experience can be had 30 minutes north of Nelson at the base of the Takaka Hill. Here the Riwaka River surfaces from an underground journey below the Takaka Hills into a subterranean cave system known as the Riwaka Resurgence.
Rising 600m above sea level, the Takaka Hills act as a natural drainage system. Fresh water flows for four kilometres underground, taking three days to get through a network of cracks and caves which have been created by the reaction of slightly acidic rain water on calcium carbonate (limestone). This limestone is actually the skeletal remains of marine animals built up over millions of years. As the earth has changed the sea bed has been uplifted and displaced. Because the dissolving process has taken literally hundreds of thousands of years it makes the environment even more unique.
Sport divers have been exploring these cave systems for many years, but for some time were only been able to penetrate a short distance; through two sumps into a large chamber. Since then the system has been explored a further 800 metres incorporating two more sumps. While this is so far the deepest penetration, it is advisable that sport divers only explore the passages mapped on the sign at the cave entrance.
The Riwaka Resurgence is well signposted from the main road between Motueka and the Takaka Hill. From the car park – a popular picnic area set amongst native bush – it is a 10 minute walk to the cave entrance. Gearing up at the car park rather than carrying gear is advised as the track is narrow and steep with steps in sections. When standing at the cave entrance only a small pool and narrow opening can be seen. However, the opening into the cave is much larger beneath the surface where a torch is needed almost immediately. The lead diver carries the penetration line and swims 15 metres through a straight sump which is 12 metres deep. The landscape is unique: lifeless, still, silent and cold. At the end of the sump, a short climb with your fins off across shallow rapids puts you in sump two. This sump is the same depth, but twice as long.
It is difficult to describe the feeling of being inside a big, empty chamber and somehow magically disappearing underneath it. The highlight of the dive is the massive chamber at the end of sump two. Here scuba equipment is removed and stalactite and stalagmite formations can be admired and explored. Photographers will appreciate the difficulty of taking pictures in an environment devoid of all but a narrow beam of relatively dull artificial light. Judging metering and distances become even more critical with the slightest error resulting in poor pictures. The sheer size of this chamber is totally unexpected; a magnificent waterfall of pink limestone cascades 20 metres or so down one side. It is inviting but donât climb it. By clambering over bus sized boulders you can walk through another small sump where the passage is narrower and the water flows with a hiss and a roar.
The return journey to the cave entrance is along the same entry route. The movement of water through the caves is just enough to ensure one good tangle of your penetration line as you wind it in. The light of day upon exiting is almost a shock as is the dramatically warmer air temperature.
The Riwaka Resurgence is on Department of Conservation administered land and is available for anyone to enjoy at no cost. However, please be aware that it is illegal for any business to operate on DoC land without the correct consent from DoC. This means you cannot pay anyone to take you through the caves. It would be disappointing to lose the use of such a unique resource because a few fail to respect the laws of the land. As with any diving environment we must preserve, conserve and protect it so that our childrenâs children will get the same experiences as we have from it.
Cave diving can be hazardous. Specific rules should be adhered to and respected:
Never leave your rope – it is your lifeline. Visibility may change quickly due to rain or siltation.
Conserve air – use one third in, one third out and a third spare. The environment inside the cave is dark and cold. This will increase air consumption.
Take at least two torches with new batteries.
Batteries other than those specified may cause the bulb to flicker and blow.
The dive should only be done with experienced cave divers who know the system you are entering.
Check all your gear before entry.
Remove your rope on the way out.
Check the weather to ensure no heavy rain is forecast. Similarly do not enter if the water is discoloured.
Take the correct length of ropes.
Look after the environment. Do not touch limestone formations or remove rocks.