cropped SEA-KIT USV Maxlimer with logos for Tonga project_edited
cropped SEA-KIT USV Maxlimer with logos for Tonga project_edited

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cropped SEA-KIT USV Maxlimer with logos for Tonga project_edited
cropped SEA-KIT USV Maxlimer with logos for Tonga project_edited

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Tonga Eruption Seabed Mapping Project - TESMaP


In April 2022, NIWA and The Nippon Foundation announced a mission to discover the undersea impacts of the recent Tongan volcanic eruption.

Phase 1 of the project (April/May 2022) saw NIWA scientists survey the ocean around the Hunga-Tonga Hunga-Ha'apai (HT–HH) volcano, covering thousands of square kilometres and collecting video images of the eruption’s impact from NIWA’s research vessel, RV Tangaroa. The image (left) indicates their unexpected discoveries.

Read NIWA's full press release here.


Phase 2, (July/August 2022) will utilise SEA-KIT's Uncrewed Surface Vessel (USV) Maxlimer to conduct a month of further mapping inside the caldera, filling in the missing pieces of the puzzle.

3D map of Tonga volcano



The eruption of the Hunga-Tonga Hunga-Ha'apai (HT–HH) volcano in January 2022 was unprecedented and unexpected. It had catastrophic consequences, covering the main island of Tongatapu in carpets of toxic ash, generating a sonic boom that travelled around the globe and causing a tsunami that resulted in deaths and damage as far away as South America. It also severed both submarine fibre optic cables connecting Tonga with the world, leaving the country in a prolonged blackout.


With similar volcanos around the globe, particularly along the Pacific Ring of Fire, the eruption of HT–HH highlights a risk to society from a lack of knowledge about them. This kind of research is vital to help protect people from similar natural disasters in the future, with the collective knowledge, experience and resources of the organisations involved helping to build a detailed and invaluable picture of the eruption’s aftermath.

Why a USV?

The use of USV Maxlimer as a configurable platform for a range of sensors provides a unique opportunity to safely gather data from inside the caldera continuously for a full month in phase 2 of the project. Sensors will be used onboard to collect bathymetric data, water column backscatter data, sound velocity, conductivity, temperature, turbidity, oxidation reduction, pressure with depth and currents, all of which will develop and support understanding of the eruption’s undersea impact and ongoing activity.


During the mission USV Maxlimer is expected to use just 100 litres of fuel per day, which is under 2% of the fuel consumption of a typical survey vessel. Deployment of a USV for survey inside the caldera therefore not only reduces risk to people, but also ensures that the carbon emissions for the project are significantly lower. The unmanned vessel will also use an innovative winch and sensor deployment capability to collect water column data down to 300m.

It is the first time that a USV will be used for this type of task and will demonstrate how the technology is pioneering new ways of understanding our oceans.

SEA-KIT USV 'Maxlimer'_edited.jpg
Maxlimer on lift_edited.jpg

The Tonga Eruption Seabed Mapping Project (TESMaP) is being funded by The Nippon Foundation – the largest non-profit organisation based in Japan which, amongst other philanthropic activities, has been facilitating projects in the ocean field since 1962.  The research is also supported by The Nippon Foundation-GEBCO Seabed 2030 Project which aims to map the world’s ocean floor by 2030.