September 2019 OES Beacon

Team KUROSHIO’s story, runner-up of the Shell Ocean Discovery XPRIZE!

Takeshi Nakatani (Beacon Associate Editor and Team Leader), Takeshi Ohki, Yuya Nishida, Blair Thornton (Beacon Associate Editor); Team KUROSHIO Board of Directors

Competition schedule of “Shell Ocean Discovery XPRIZE.”

Team KUROSHIO is a joint research team taking on a global competition “Shell Ocean Discovery XPRIZE.” Among the 32 teams from all over the world, Team KUROSHIO finished 2nd in the grand-final, and were awarded the runner-up prize. The team members come from eight different organizations, including government research institutes, universities, and private companies*1, all with a background and passion for marine robotics, sensing and deep-sea exploration.

The ocean covers 71.1% of the Earth’s surface, but to date, only around 10% of the ocean floor has been mapped. In other words, we do not really know what is out there for about two-thirds of the surface of our own planet. The competition challenged teams to think differently, and advance deep sea technologies for autonomous, fast, high-resolution ocean exploration. This article introduces our team’s story, and reports on our testing in the final round held in Kalamata, Greece in December 2018.

Team KUROSHIO. A joint research and development commu-nity by eight Japanese organizations.

Our journey started 1009 days before the prize ceremony, on the Island of Maui, Hawaii, on 25 August 2015. A member of what would become Team KUROSHIO had just presented some data collected by a Japanese Underwater Vehicle in the Iheya North Field, off the coast of Okinawa. Jyotika Virmani, Executive Director at XPRIZE, came up to us and told us about the new concept she was developing, an XPRIZE competition for deep-sea mapping. At the time, the details were still being worked on, but what was for certain was that it would involve mapping huge areas of the seafloor using underwater robots, probably several of them. In December 2015, the XPRIZE was announced, and Team KUROSHIO was born. The challenge set was for robots to map a huge region of 500 square kilometers, the size of a large city, at a resolution high enough to spot a car, at a depth deeper than the height of mount Fuji. The real challenge was that this all had to be done in 24 hours, with no ships or people to support the robots during the entire operation.

Mission strategy of team KUROSHIO.

Team KUROSHIO started out as a series of meetings where a handful of young engineers met and brainstormed. We exchanged hundreds of ideas, drew thousands of sketches, we challenged each other and ruthlessly eliminated concepts that weren’t robust. We also realized that the challenge required more than just good technology. It required us to be organized. We formed a board of directors, a development group, an operations group, and management and communications teams. We grew from a handful of young engineers into a team of more than 30 engineers, administrators and publicists spanning academia, government and industry.

Through the three-years of international competition, there were three gateways teams had to battle through. The first, was the technical proposal and document review. Next was the Round 1 technology readiness test, which included hardware demonstrations in water. The final gateway, Round 2, was the sea-trials. The Round 1 technology readiness test was held from November 2017 to January 2018. The competition judge evaluated each team’s technology across 11 criteria, in each team’s home country. Round 2 tests were held from November to December 2018, where eight teams, including Team KUROSHIO, had advanced to the final stage. The competition judges evaluated each team’s seafloor survey performance through sea trials in the Mediterranean Sea.

The mission requirements of Round 2 testing are as follows:

  • Operators have to stay onshore, operate the team’s survey system from a land-based mission control center.
  • The entire survey system has to fit into single 40 ft container.
  • The survey system has to be launched and recovered from a shore base and make their own way to the survey site.
  • The teams need to acquire bathymetry of 5 m resolution horizontally and 0.5 m resolution vertically at the site. Several seafloor images also have to be captured.
  • The survey system has to acquire a minimum of 250km2 of bathymetry up to 4,000 m depth in 24 hours.
  • The seafloor map must be extracted, processed and outputs submitted within 48 hours.
Bathymetry data acquired by Team KUROSHIO during Round 2 (Lower left) Extended figure of the bathymetry.

To satisfy the above missions, Team KUROSHIO proposed a compact and mobile suite consisting of multiple robotic systems capable of fast and ultra-wide area bathymetric survey without a crewed support vessel. The proposed system consists of two autonomous underwater vehicles (AUVs), an autonomous surface vehicle (ASV), and ground mission control. The proposed system includes a system that enables towing, deployment and recovery of AUVs by an ASV without the support of a crew. The ASV can tow multiple AUVs from shore to the competition area and release the AUVs once at the site. The released AUVs dive down to an altitude of ~100m and follow pre-programmed waypoints. The land-based operators monitor the AUVs’ status via the telemetry suite on the ASV, which communicates with the AUVs using underwater acoustics, and communicates with the land-based operators through satellite communication. The bathymetry data is saved on hard disks inside AUVs, which are extracted and processed after the AUV recovery.

Team KUROSHIO conducted Round 2 testing between December 9-19, 2018, in the midst of the Greek rainy season, with spurts of activity taking place between thunderstorms and gales.

12/1: Team departs for Greece.

12/10-: Final systems tests for robot mission control. Decision made to carry out Round 2 testing with our ASV and the AUV-NEXT due to hardware trouble.

12/16: Round 2 testing off Kalamata. The ASV towed the AUV 15 nautical miles to the competition area and then released the AUV. Subsequently, the AUV started seafloor survey for 24 hours.

12/17: After 24 hours, the AUV finished the survey and returned to the mission control, the port of Kalamata. The acquired date was extracted from hard disks inside the AUV and was handed over to the team’s data processing group.

12/19: Team completed the data processing and submitted the data products to the judges.

We succeeded in acquiring bathymetry data over a 5 by 33.5 km region, at 1 m lateral resolution using AUV-NEXT’s multibeam sonar. Several side scan images were also acquired and submitted.

On May 31, 2019, the Shell Ocean Discovery XPRIZE award ceremony was held at Oceanographic Museum of Monaco. XPRIZE announced that team KUROSHIO won the runner-up prize in the Grand final and awarded our team the “official” prize of $1M and a trophy, where the latter was unfortunately held in customs.

Team KUROSHIO’s vehicles and equipment: ASV, AUV “AUV-NEXT,” AUV “AE-Z,” and communication equipment on the ASV being setup.



AUVs being towed by an ASV near the port of Kalamata, Greece on Dec.11, 2018.
Data submission ceremony of team KUROSHIO on Dec.19, 2018.


Departure of an ASV and AUV from the port of Kalamata, Greece on Dec.16, 2018.
Return of the ASV after 30 hours unmanned navigation on Dec.17, 2018.


We appreciate the XPRIZE foundation and Royal Dutch shell for the opportunity that they have provided us and the marine research community. We thank our sponsors, suppliers and supporters. It was an intense, unforgettable, and valuable experience. For us, the “real” prize was the journey XPRIZE took us on; the sense of achievement in seeing ideas that were first sketched on scraps of paper play out in Kalamata for the whole world to see; the thousands of supporters following our activities on Facebook and twitter and the tens of thousands of likes we got on YouTube; the fact that marine robotics has become a more familiar term to everyday people around the world; and most importantly, the opportunity it gave for the members of Team KUROSHIO to work closely alongside each other, because these people are the community of engineers, operators, administrators and publicists who will drive the next generation of marine robotics research in Japan.

Team KUROSHIO received the Runner-up prize for the Grand final at the Shell Ocean Discovery XPRIZE Awards Ceremony on 31 May at the Oceanographic Museum of Monaco.