Digest of Research Done
around Okinotorishima Islands

Expedition dates: December 2 to 10, 2021
(field work done on December 5 and 6)

December 2, 2021, early morning
Researchers gathered together and boarded Tokai University's oceanographic research and training vessel, Boseimaru.
At 8:00 a.m., Boseimaru left the Port of Shimizu for Okinotorishima Island.
The Boseimaru, carrying 56 researchers, headed about 1,700 km south.

The boat arrived in the Okinotorishima Islands area in the early morning on December 5, exactly three days after it left the port. Researchers then started field work.
They changed the study schedule after each general meeting, based on the weather and water conditions.
(Visual study) They could see the observation base facility located on the western side of Okinotorishima Islands, which spans about 4.5 km from east to west.
(Visual study) They could see an islet protected by a seawall, about 50 m in diameter.

They changed the study schedule even more on the second day of field work because of continued strong winds, high waves, and surges.
(Ocean study) Researchers started collecting surface water for water quality measurement.
(Ocean study) They started using a small sensor (XCTD) to measure water depth, temperature, salinity, and more.
(Visual study) A drone took aerial photos in the short time that the strong winds died down.
(Ocean study) Researchers used white discs and other items to confirm the water's transparency.
They left Okinotorishima Islands, surrounded in white by the waves, on December 6 for their three-day trip home.