Ellis Basin Cave Expedition Jan 9-21

I emerged from the Red Hills and enjoyed less than 24 hours of civilization before I was off again to be flown into the Ellis valley with a team of 5 other cavers. Our goal was to push the Ellis Basin Cave System past its 775m depth to over 1km.

With the cave extending under 1800m peaks and a resurgence dived to an elevation of about 90m, the cave has a substantial potential for an internationally significant cave, let alone the greatest depth potential of any known cave in New Zealand. This is easier said than done as all the passages at the bottom of the cave are sumped (i.e. filled to the roof with water) and the highest portions of the cave require bolt climbs up walls of tricky and loose rock. The cave is one of the most physically demanding I have ever been in.

This expedition would last 3 weeks and was well-funded which allowed several trips with the helicopter to ferry our mountain of gear up to the Ellis. We set up camp in a beautiful bit of bush conveniently located next to the stream and the routes to the cave's entrances. Our camp was quite plush; we had a 3-room tent, generator, gas lanterns, whiteboards, a wall-sized map of the cave, a laptop, solar panels, and even a solar shower. We were well-stocked with caving gear (over 500m of rope, 200 carabiners and 50m of PVC pipe) and with copious amounts of food.

Above: View from North Twin along the Arthur Range. Tablelands in background. Note person at center right.

Ready for pickup. Arthur Range in background.

The entrance series in Exhalabur drops over 200m on rope. Several more pitches, handlines, climbs and traverses exist before pleasant walking passage gave way to a formation squeeze which soon after finds you in the top of a deep canyon passage with the main stream thundering below. The main streamway was wet and sporty with waterfalls and pools to avoid as best as possible. The cave has a little bit of everything.

I exited the cave on the first full day completely destroyed and it took me quite some time to do a simple task like dressing in dry clothes and to feel human again (I had not felt this spent since the 4 day Bulmer Cavern trip I did in 2006). To my relief it was not just me- the whole team felt the same- and the next day was declared a rest day. Because we had a lot of hard out days of caving, we also had a lot of rest days. Rest days were spent either improving camp (chairs, tables, irrigation and a fire pit) or scrambling around on the karst. I could have met my death when a few of us were scrambling up Winter Peak. One of the other two was 50m directly above me when he managed to dislodge a car engine-sized rock. I immediately reverted to adrenaline-fueled instinct and according to the third person, he had never seen anyone move so fast over such uneven terrain. I took off at a full sprint laterally. The rock broke into 10 bowling ball-sized blocks, each of which could have killed, a few of which just narrowly missed me. I spent quite some time sitting in an odd hyperactive stupor until the drugs wore off. Pretty exciting for a rest day!

Enjoying camp on a rest day

The second full day into the cave we carried 50m of 3" PVC pipe to the bottom of the cave to try to drain a sump. Some of the team spent quite some time trying to get the siphon going with very little success. Meanwhile I was getting bored and cold so I started to wander around. I found a small streamlet flowing over a flowstone waterfall so I ran back to get a rope. Once down the short drop the only way on was through a low hole between formations underneath the flowstone I came down. Through the gap was a deep blue pool of crystal clarity that on closer inspection could just barely be skirted using ledges and formations. Once past this gateway, every step was pure never-before-seen delight- beautiful crystal pools, sparkling white flowstone, large curtains and stals and large pendants with bulbous ends from being dipped in former pools, all in a tall canyon passage. I continued until the passage turned into a steeply-descending flowstone-floored tube. It was going down!

In Pipe Dream (photo by Kieran McKay)

I ran back to get the others and told them to stop draining the sump. We moved the piping to drain the 1001 Bucket Sump, which when lower, would provide us with a significant shortcut bypassing the main streamway. We then split into two groups, mine to continue exploring and the second to follow by surveying. My discovery went 300m straight east (good) to yet another sump (bad). I decided to call this passage "Pipe Dream" because of the amusement with the PVC pipes and because of our hope that it would lead us deeper. It is the most beautiful passage I have seen in the cave. We also found abundant evidence that this cave floods up to 150m above the lowest known part! I do not know of any other cave in the world where this can happen.

Since this sump was now the most promising lead, the others dragged dive gear and our diver dove the sump. The same day I hiked out to head back to Dunedin. That evening I found out that they were hiking out to get wetsuits which piqued my interest so I stuck around. It turned out the sump was only 3m long with going passage on the other side so they were planning on free diving it. Desperately wanting to know where my passage went and wanting to be a part of its exploration, I repacked all my gear I just painstakingly cleaned and flew back in with the others. And so less than 24hours after hiking out I found myself back on the mountain. Coming back was a bit surreal.

Armed with wetsuits we free dove the sump the following day. For being only 3m long, I felt a whole world away being on the other side of it. This passage continued in a huge assortment of passage dimensions with several pools to cross and beautiful formations in abundance. Unfortunately we were greeted by the most spectacular sump pool I have ever seen. It was a deep crystal blue pool, 34m long and more than 9m deep. We were not going to be able to free dive this one! We surveyed over 500m of passage in this area that became known as Wet Dream.

In Wet Dream (photo by Kieran McKay)

We also checked leads in a wet and muddy area called Death By Chocolate and some climbing leads near 1001 Bucket Sump. We then shifted our focus to the top of the cave, attempting to re-find a cave known simply as EK3010 (which turned into a nice alpine karst appreciation day) and rigging the Tomo Thyme entrance series. We then went into Tomo Thyme to try some climbs in a wet and very cold part of the cave known ironically as Blue Hawaii. Here we hid under an alcove as a shower of rocks bounced around us from the climber working his way up the loose rock.

Exploring an undescended shaft

I left to hike out the next day, but several more discoveries were made in the final week of the expedition. Although no deeper, several great advances were made that will probably lead to a crucial connection or two soon.

Atop the north Twin

Some views of the alpine karst: