Secrets of Lake Taupo

Lake Taupo’s Secrets Revealed


special report by Keith Gordon on the recent submersible expedition

Lake Taupo, New Zealand’s largest lake, was recently the focus for underwater exploration by the Lake Taupo JAGO Dive Project, organized and funded by the Institute of Geological and Nuclear Sciences Ltd (IGNS). The two-person JAGO submersible, owned by the Fricke Research Group of the Max Planck Institute, was brought to New Zealand by a consortium of German universities to explore the deepest area of the lake, recorded as 165 metres, close to the Horomatangi Reefs. The 600 square kilometre lake, situated in an area of thermal activity, is the location of the world’s most active rhyolite volcano, which has erupted 28 times in the past 27,000 years. The eruption in 181 AD which created the lake was the most violent eruption on our planet in the past 5000 years.

It was the vent from this eruption near the reefs that was the centre of attraction for the Project scientists. Gas bubbles had been observed rising to the surface in this area over past years, and remote sensing had revealed bottom features that could possibly be hydrothermal vents. It was planned to explore the area with JAGO to gather samples of gas and hot water, collect rocks and sediments, and record on video observations of the lake bed.

I was most interested to read media reports of the intended exploration, and contacted minerals geologist Cornel de Ronde, leader of the project at IGNS. Cornel invited me to join the team at Taupo with my Remote Operated Vehicle (ROV) to support the JAGO operations. My old diving buddy Wade Doak, and diver Tara Ross-Watt from Tauranga, joined me to assist in the ROV operations. As we headed south in a van loaded with ROV systems and pulling a trailer with a 360m reel of ROV tether cable, Wade and I recalled our early days diving in the 1950s and the amount of gear we then carried when setting off for a diving trip. We were now a far cry from those days of mask, fins, snorkel and speargun! The sight of the bright yellow JAGO submersible brought to mind the Beatles song, and visions of all the wonderful underwater excursions one could carry out with such a machine. It was therefore of some concern to learn that the sub had sat in storage in Auckland for two months before commencing the Taupo project. Think of the exploration that could have been carried out during that period if it had been known that such a machine was in New Zealand!

Built in 1989 in Germany, the two-person, 3.2m long, 3033kg sub has an operating depth of 400m. The large acrylic nose dome viewport and hatch dome provide the crew good vision, and the hull interior, although packed with systems, provides ample room for crew comfort during an average three to four hour dive. Power is supplied by 24 volt batteries for the three reversible stern and two side thrusters, halogen lights and support systems. A hydraulic eight-function manipulator provides the ability to carry out work, including collection of samples, and a small three-chip video camera is mounted on the claw for closeup filming. The crew also operate a three-chip digital camcorder for recording video through the viewports. Due to the lack of a suitable boat with lifting gear on the lake, JAGO was launched by crane from Moturere Bay and remained in the water for the duration of the project, being towed to the dive sites as weather conditions permitted.

JAGO was piloted by Jurgen Schauer, who is the Group Fricke engineer and technical leader. He was accompanied by Karen Hissmann, zoologist, research assistant and administrative manager for the group. Jurgen has carried out over 480 dives with JAGO, including studies of the coelacanth, a fish once thought to be extinct, on the steep slopes of the volcanic Comores Islands.

Jurgen recalled an occasion during a recent expedition off Guam when he was caught in an underwater hurricane while diving on a sea mount in JAGO. The tiny sub was tossed about the slopes by strong deep ocean currents, then was suddenly engulfed in a dust storm of billowing sediments. JAGO finally emerged from this onslaught minus some of the yellow paintwork left on the reef. Taupo is not subject to ocean currents; however, there is always the possibility of earthquakes and volcanic activity, perhaps including some very hot water. The IGNS scientists had plotted indications of increases of bottom water temperature, and depth recordings also indicated considerably greater depths than the maximum 165m chart recordings. These were areas the scientists were most interested to investigate. Representatives from the Tuwharetoa Maori Trust Board were also keen for the lake depths to be explored and supported the IGNS JAGO project. The trust, as owners of the lake, wished to know more about the ecology, geological features and geothermal activity in the lake.

It was thought that perhaps the reason why many large trout inhabit the reef area could be hydrothermal activity producing additional nutrients. Wade and I had some discussion with Rakeipoho Taiaroa, the trust secretary, on the many questions about the lake that awaited answers, and of possible future developments that such answers might unlock. It was most encouraging to discover the keen interest by the trust and the responsibility for the lake they had undertaken.

Strong winds from storms that were causing havoc further south disrupted the dive program and after delays, JAGO finally dived in an area where gas bubbles had been observed on the surface. With Cornel as observer, Jurgen submerged JAGO beneath the choppy lake surface. On the bottom, excitement increased as a stream of gas bubbles was discovered erupting from the bottom, and then another. However, the best was yet to come. As the sub maneuvered over the bottom, the edge of a depression was illuminated as the light beams reached out into the darkness. It is a dramatic moment to see recorded on video, as the sub hovers over the lip of this basin area. Numerous plumes of gas sprout from the bottom sediments like silver fountains, reflecting the sub’s lights. It is a scene from science fiction – life forms in an alien world – but it is real and here in Lake Taupo. Cornel, crouching in the nose dome, is astonished as the scene is suddenly revealed before them. ‘Holy shit!’ he shouts, not really a scientific description but certainly apt for the occasion.

After all the planning and frustrations, the project has suddenly become a success as scenes never before seen are revealed in the 170m depths. Gas samples are collected; in some instances the gas is flowing so strongly that the special collection containers are quickly over-filled. Rock samples are collected and strange formations studied. Koru (freshwater crays) also inhabit these depths and march aggressively, almost alien-like, across the bottom in the glare of the lights. A small fish is followed with the video camera and Jurgen exclaims that it is similar to a species he has observed during dives in the volcanic lakes of Iceland.

After a three hour dive, JAGO surfaces and divers carefully remove the collected samples for analysis and study. On the next dive with Auckland University petrologist Pat Browne as observer, a depth of 184m was reached, beyond the charted maximum depth. Here, columns of hot water rising from the bottom with temperatures of 44°C were recorded. Hydrothermal chimney vents were discovered, with growths of unidentified white sponge-like organisms. Described by Jurgen as ‘like a little lollipop’, samples of which were collected for study. Taupo has revealed some of its secrets, and future explorations using ROV technology will no doubt reveal further exciting scientific discoveries. These discoveries shall also be of benefit to the Tuwharetoa Maori Trust with their endeavours to plan for the future protection and development of the lake’s resources.

Prior to the Taupo JAGO Dive Project, the submersible took part in a scientific exploration of the ocean bottom around volcanic White Island. New Zealand and German scientists working from the German research ship Sonne made startling world-first discoveries during the voyage. Some phenomena associated with hydrothermal vent activity are normally found only in depths of 2000m or more; around White Island they were found in depths of 140m, well within the capabilities of relatively inexpensive ROV technology. One startling discovery was made from rocks recovered from the area. Exposed to the reduced pressure on the surface, globules of mercury oozed from the surface of the rock. This had never been observed before. The oceans around New Zealand offer opportunities for many discoveries to be made, and development of technology for exploring ocean depths could become a major New Zealand industry. With government support, education programs and corporate funding, New Zealand is well situated to be a major player in future underwater exploration. Our Exclusive Economic Zone is the fourth biggest in the world and we therefore have an obligation to develop and explore these underwater domains. The Tuwharetoa Maori Trust recognize the role they have with the development of Taupo, and accept that this does not stop on the surface. The IGNS also, by bringing JAGO to New Zealand, recognize there are exciting discoveries waiting below the surface of our seas. More of such exploration will be of benefit to all New Zealand, as we advance into the new millennium.

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