Water/Hycean Worlds & Oceanography

Chinese And New Zealand Scientists Dive to One of the Ocean’s Deepest Regions

By Keith Cowing
Press Release
Chinese Academy of Sciences
December 4, 2022
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Chinese And New Zealand Scientists Dive to One of the Ocean’s Deepest Regions
Human Occupied Vehicle Fendouzhe retrieved by Tansuoyihao Image by IDSSE

A submersible pilot from China and a New Zealand scientist have become the first women to dive to Scholl Deep in the Kermadec Trench, 10 km below sea level.

The dive was undertaken by NIWA (National Institute for Water and Atmospheric Research, New Zealand) marine biologist Dr. Kareen Schnabel and submersible pilots DENG Yuqing and YUAN Xin from the Institute of Deep Sea Science and Engineering (IDSSE) of the Chinese Academy of Sciences (CAS).

It was only the second crewed visit ever to explore the Scholl Deep and was done as part of a two-month scientific voyage on board the IDSSE’s research vessel Tansuoyihao.

Scholl Deep is the deepest known point of the Kermadec Trench, which lies to the north of New Zealand. The 1000 km plus long trench is almost perfectly straight, and its deepest point is at a depth greater than the height of Mt Everest.

Using the Human Occupied Vehicle (HOV) Fendouzhe, scientists collected deep-sea water samples, sediments, rocks, biological samples, and environmental data.

Bamboo Coral at about 5700 metres below sea level (Image by IDSSE)

Dr. Schnabel and the submersible pilots spent six hours at the bottom of the sea exploring the Scholl Deep and the steep sides of the trench.

“This extraordinary submersible technology has given us the privilege of studying parts of the ocean in ways that we aren’t usually able to, giving New Zealand researchers a rare chance to explore this fascinating and fragile environment,” said Dr. Schnabel.

“Textbooks and images don’t compare to experiencing the light disappearing as you leave the surface of the ocean or seeing the deep sea floor with your own eyes. The fine sediments were covered in tracks, and we saw lots of small animals on the sea floor and in the water. It was jarring that there was still rubbish such as fishing floats and nets, even though we were more than 10,000 m below sea level,” she said.

The first leg of the voyage was successfully completed on 24 November 2022. The HOV Fendouzhe undertook 16 dives between the depth of 5,747 m and 10,000 m, in addition to the deployment of other independent samplers such as a lander, CTD (water sampler), and a gravity corer.

Rocks covered with a variety of organisms at water depth of about 6000 meters (Image by IDSSE)

“It is really exciting for both Chinese and New Zealand scientists to have the opportunity to comprehensively appreciate the complexity and diversity of both the geo- and ecosystem of the Kermadec Trench,” says Dr. PENG Xiaotong, the leader of this voyage from IDSSE.

“Taking rock samples, for example, offers us a unique chance to understand the nature of the subducting and overriding plate, as well as the mechanism of the subduction initiation in Kermadec Trench,” said Dr. PENG.

“A number of the animals have been tentatively identified and are either presumed new to science or have not been seen or collected since the first sampling voyage by the Danish research vessel Galathea in the 1950s.” said Dr. Schnabel.

“It was fascinating to actually observe the tiny sea cucumbers at the bottom of the Kermadec Trench, which are three times smaller in size than those we have observed previously in the Mariana Trench. These sorts of differences between trenches show that mysteries remain as to how animals are adapted to live in extremely deep environments,” said Dr. ZHANG Haibin, a marine biologist from IDSSE.

IMAGE Sea anemone at about 9,000 meters under sea level (Image by IDSSE)

The vessel has returned to Auckland for re-supply and staff change-over. The second leg will be completed before the end of December with another 16 dives planned. The voyage includes scientists from NIWA, IDSSE, Shanghai Jiaotong University, Tongji University, Zhejiang University, Hainan Tropical Ocean University and BGI-Qingdao.

NIWA scientist Dr Daniel Leduc, who dove in the submersible in the north of the trench at 9110 m, said the samples obtained represent a step-change in our understanding of the biodiversity of New Zealand’s deepest marine environment.

“We saw highly diverse seafloor communities even at great depths and discovered strange and rarely seen organisms such as the upside-down angler fish. As we go deeper into the trench, seafloor ecosystems become dominated by small organisms, which will need to be examined using light and electron microscopy back on land. I expect we will find many new species,” he said.

IDSSE and NIWA will continue their collaboration following the voyage to analyse the large number of samples obtained to give a better understanding of New Zealand’s deepest environment, and the impacts that humans may have on it.

Polychaete at about 7500 meters below sea level (Image by IDSSE)

About the Kermadec Trench

The Kermadec Trench is approximately 1000 km long and 120 km at its widest. It runs from the East Cape of Aotearoa New Zealand towards Tonga, where it continues as the Tonga Trench. The Kermadec Trench is formed by the subduction of the Pacific Plate under the Indo-Australian Plate. It is one of the deepest trenches worldwide, with its deepest point approximately 10,000 m deep below the ocean surface.

About HOV Fendouzhe

Manned submersible that is capable of diving to 11,000m depth carrying three personnel. It is used for observing the bottom of the sea, taking HD video, and collecting rock, sediment, and biological samples. The duration of routine HOV diving is around 12 hours, and for a routine dive the HOV is deployed in the early morning and recovered late in the same day.


IDSSE is an oceanographic research institute devoted to deep-sea scientific research and the development of new deep-sea technologies. Two Human Occupied Vehicles, Shenhaiyongshi and Fendouzhe with maximum operating depths of 4,500 m and 11,000 m, respectively, are managed and operated by IDSSE. Together with two research vessels and series of deep-sea landers, they form the integrated deep-sea research platform open to the public. Global Trench Exploration and Diving programme (Global-TREnD) was recently initiated by IDSSE to advance humanity’s understanding of the geology and biology in the deepest parts of the world’s ocean.

About NIWA

Crown Research Institute NIWA is New Zealand’s leading environmental science and applied research service provider, specialising in atmospheric, freshwater, and marine research. NIWA work at the forefront of some of the most critical environmental issues facing the planet, and our staff are recognised as international experts in their fields.


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