Text and Photography by ADM’s Australian staff photojournalist
Richard Harris
The massive collapse that marks Kija Blue is nearly 300 feet in length, and bordered by sheer 70-100 foot high walls.
Above: High noon sunlight floods the cave entrance, illuminating the cobalt blue water as the dive team descends deep into the darkness.

Paul Hosie gathers equipment after the 60-foot rappel into the cave entrance, the easiest and quickest method to gain access to the subterranean lake.

Above: Paul Hosie “posts” himself down the slot to access the massive chamber below.

A lone fly drank from the tiny pool of moisture in the corner of my eye. I swatted it away, then stretched and yawned as the dawn broke in the Australian Kimberley. There really was no need to slake its thirst on me, for just 200 metres to the north lay a cavernous body of water, perched within the ancient red sandstone and dolomite of the arid northwest. A massive sinkhole or cenote, many miles from the remote township of Warnum was the reason for our makeshift camp in this loneliest part of Australia. Swags and wetsuits marked the temporary home of the six explorers who came from different corners of the country with the common goals of discovery and adventure…

It was clear from the somewhat disorderly campsite that camping was not the focus of the group. Over at the sinkhole, the scene was different. Mixed gas closed circuit rebreathers (CCRs), masks, fins, reels, slates, and the other tools of exploration cave diving were arranged in neat piles by each diver in readiness for the day’s mapping work. Everything prepared, then checked and double-checked before a dive into the spectacular unknown of Kija (pronounced “gidja”) Blue.

Just six years before our visit, local caver John Storey located and dived the site in a quick single tank sortie. So stunned was he by the beauty of the cave, he vowed to protect it by keeping its location a secret. In 2005, after some clever detective work by the local cavers, Paul Hosie, Paul Boler, and Ken Smith spotted the cenote from a light aircraft. They then visited the sinkhole for three short days as part of a larger caving trip. Expecting nothing more than a small lake in one corner, they planned only three or four short dives to document the site and tick it off Paul’s long list of possible caves. But what they saw in those brief dives amazed them; an azure blue cenote of such clarity, size and depth that they knew they would need to return for a larger and better prepared expedition to fully document the extent of the cave. In addition, the depth of the site (over 75 metres in one area) meant that more sophisticated equipment and techniques would be required to safely perform the exploration and survey work. With this in mind, Paul Hosie assembled a team of six experienced “technical” cave divers who could undertake the dive. A highly proficient team traveled to the farthest reaches of the Kija people’s traditional land.

Paul Hosie, one of Australia’s most prolific cave explorers, has discovered and documented literally miles of submerged passage, especially in the arid Nullarbor region, the Roe Plains, and the Ningbing Ranges of the northern Kimberley. Also from Perth, veterinary surgeon Craig Challen can claim to be one of the very few divers to have ever seen the final sump of the famous Cocklebiddy Cave on the Nullarbor Plain, over 6 km from the cave entrance. The third member of the Western Australian contingent was Steve James, an exNavy diver with extensive deep CCR diving experience. From the other side of the country came the “East” team: John Dalla-Zuanna (“JDZ”), one of Australia’s most experienced cave divers, instructors and deep CCR divers; Ken Smith, the softly spoken, humorous Adelaide nuclear physicist who brings not only enormous caving experience to the project, but also a myriad of home-made electronic radiolocation gadgets (“Pingers”) to assist with the cave surveying. And finally, yours truly, an Adelaide doctor, a CCR diver, and underwater photographer!

So six cavers from around Australia met to participate in an amazing adventure, to dive in, survey, and document in detail what could be the remotest dive site in the world. Remotest dive in the world? A big statement, but one needs to understand a bit more about this part of Australia. The Kimberly in Australia’s northwest, an area of over 423,000 square kilometers (larger than the UK), has a population of less than 40,000 people, most of whom live in the few major towns like Broome and Kununurra. It is a very large and empty place! Once on site, we were very much on our own, so preparation was all important. After meeting up in Kununurra, we transported all the equipment down to a nearby airfield. From there, six helicopter flights would transport us and all our equipment out to the cave where we camped for 10 days. Everything we needed was on the choppers. Food, clothing, dive equipment, mixed gas supplies, communications, first aid, photographic and survey equipment, compressor, and generator…the list seemed endless. The only thing we didn’t need was water; there was plenty of that!

The Kimberley can lay claim to some of the world’s most ancient geology. The Proterozoic sandstone and dolomite that holds the cenote is 1400 million years old. The massive collapse doline that marks Kija Blue is nearly 100 metres in length, and bordered by sheer 20-30 metre high walls. The heavy equipment was lowered over one of the precipitous walls to the base, and then carried down the boulder slope to the water’s edge. Each night we mixed our precise cocktail of helium, nitrogen, and oxygen so that all would be ready for the morning. Before every dive, it was analysed with a Dive Rite Analox trimix analyser to double-check the contents of the breathing gas.

The group divided themselves into buddy pairs for the exploration work: JDZ (Prism CCR) and Harry (modified KISS CCR) as one deep team; Craig and Steve who both dive the Megalodon Rebreather comprised another. Paul and Ken gave shallow support and performed survey diving to 60 metres depth. One of the major obstacles to the planning of remote deep diving like this was our ability to transport in sufficient bailout gas in SCUBA cylinders for use in the event of a primary rebreather failure. The limited payload weight of the Jet Ranger helicopter meant that every kilo had been counted long before we even arrived in the Northwest. Our approach to this problem was the development of 2 “BOBs” or bail-out rebreathers. Not a completely new concept in the world of rebreather diving, but certainly amongst the first to be used in Australia, especially in the side-mounted configuration. The two new rigs had been tested by JDZ and I during shallow cave and ocean dives, but holdups with their development meant that R&D was definitely ongoing! One deep team was in the water at a time, with the second assisting them and preparing for their own dive. Unfortunately, problems with the new BOBs would prevent them playing any major role in the exploration (i.e. they broke!).

Craig Challen and Paul Hosie conducting their final equipment checks before the large push dive to over 110m / 364ft deep.
Above: JDZ emerges from the silt as he takes survey measurements in the “Colossal Room,” depth 60m/200ft.

Above: Craig Challen with the Megalodon rebreather prepares for a deep dive. The full facemask is insurance against the risk of convulsions when exposed to high levels of oxygen…one of the dangers of deep rebreather diving.

The helicopter flight out to the sinkhole offered breathtaking views of the golden sandstone, waterholes, and ravines. After an initial flurry of activity unpacking and setting camp, we quickly developed a routine. Out of our swags at around 5 a.m., coffee and porridge before hiking up the rocky hill to the sinkhole with freshly charged rebreather cylinders, batteries, and CO2 absorbent for the day. The Kimberley dawn warmed our bones after the near-freezing nights. Gear was lowered into the hole, followed by a 20 metre abseil to the top of the talus slope. A further 25 metres down the unstable talus to the lake edge with all the gear, and we were well and truly warmed up!

Based on the rudimentary map made by last year’s expedition, we commenced a systematic exploration of the cave. Using hundreds of metres of pre-knotted line, divers swam out in a radial pattern over the ensuing days to find and map the farthest reaches of the cenote. Massive, bus-sized boulders lay strewn about from the collapse of the dolomite into the lake chamber. Working our way between them, they created a complex labyrinth within the hole. Over the subsequent days, divers started to return with depth measurements of 75, 80, 90, and then, finally, 106 metres. Trying to lay line in the increasingly narrow, deep, and silty conditions at the back of the cave became more and more challenging. Line once laid, was surveyed on the return journey to gradually build up a picture of the enormous chamber. After initially performing two dives per day, the deep teams dropped back to single daily dives as the cave became deeper and dive times ran out to three and four hours. We staggered back into camp around 5 p.m. on most days to begin the chores of gas mixing, battery recharging, and data entering before a quick meal, a glass of boxed red, and collapse into bed to do it all again the next day!

By day, we were treated to a spectacular light show as the sun shone down into the cave lakes; by night, the sky was lit up by the Milky Way in all its glory, and the Capricornids meteor shower. What a truly beautiful place. As I wrote this, I sat under the brilliant stars, wearing a net over my head to keep a sudden swarm of tiny moths from my nose and eyes as they bathed in the light of the laptop! Ken was next to me entering data from his pinger points and the day’s survey lines into the map. The rest of the team was already snoring, and it was only 8:15 pm!

As the week progressed and the dives became deeper, the cave became tighter and siltier in the areas of rock collapse below 80 metres. From this point, we began to dive solo because of the risk of silting and entanglement whilst in buddy pairs. After six full days of diving the cave was beginning to reveal its secrets, with the furthest extent several hundred metres down the ridge south of the doline, at a maximum depth of 111 metres. At this level, the cave passage through the boulders was continuing and the talus slope was slowly but steadily dropping. We certainly had a major cave system on our hands — and only two full diving days left!

As is often the way on these trips, the best parts of the cave are only discovered towards the end of the expedition. With time running out, we were into a major tunnel at significant depth, with dives now running out to between 4 and 5 hours! The use of a scooter made the 300-400 metre swim down to the exploration area quicker, but it was still fairly arduous.
John Dalla-Zuanna (JDZ) pauses to assemble survey notes during an exploration dive in Lake 2.
Above: JDZ surveys along the line on the way out of the cave. By measuring the angle of the line and the floor and roof depth at certain points, a picture of the cave is gradually built up.
Above: Steve James returns from a deep exploration dive with his Dive X-Tras scooter..

The risks of decompression illness (DCI) are theoretically high doing multi-day deep dives, followed by significant exertion. In fact, each of the four deep divers experienced some symptoms of DCI and also probably pulmonary oxygen toxicity during the week. “Niggles” requiring extended decompression or surface oxygen occurred on two occasions. Profound fatigue and itchy skin occurred in two other divers. A dry cough and breathlessness were seen after three dives. But in four divers performing over 20 dives in total between 80 metres and 111 metres, this was felt to be acceptable. However, it shows that even with relatively conservative dive planning, good attention to hydration, no alcohol, and plenty of sleep, multi-day deep diving is not without risk. The team was both prepared and trained to perform in water recompression in this remote location for a more serious episode of DCI, and a disaster plan was lodged with local emergency services and the nearest chamber.

Day 10 and with the diving finished, a long day of extracting all the gear from the cave and flying back to town in the helos was followed by more than a few celebratory beers! We were pleased that we had safely explored and mapped a large part of this enormous and beautiful site in the remotest part of the Australian outback. Water, rock, and fauna samples had been sent to the Western Australian museum to further increase the existing knowledge of the cave. And the best part of all? The big question mark on the map at the bottom of the cave that means we’ll have to do it all again next year!


The team would like to acknowledge and thank the local cavers in Kununurra who “rediscovered” the cave: John Cugley, Dave Woods, and Donna Cavlovic. Their generosity and passion for caving and cave conservation is second to none. Thanks to our major sponsors Seaoptics Adelaide and Dive Rite Australia for their tremendous support. Thanks also to CCR Diving in Perth and John Lippmann from DAN Asia Pacific.
JDZ and Richard Harris swim out of the “Colossal Room,” at a depth of 200 feet, surveying as we go.