Police officers search for missing passengers of the Kazu I tour boat along the Shiretoko Peninsula in Hokkaido on May 16. (Video by Hiraku Toda)

ABASHIRI, Hokkaido--A vessel equipped with special saturation deep-diving equipment entered a port here on May 17 before departing to search a sunken sightseeing boat for 12 people who were aboard and remain missing.

The private-sector working vessel Kaishin left Moji Port in Kita-Kyushu, Fukuoka Prefecture, on May 10 to investigate the interior of the Kazu I and prepare for the salvage effort.

The sightseeing vessel sank off the Shiretoko Peninsula, eastern Hokkaido, on April 23 in rough seas with 26 people on board. So far, 14 bodies have been recovered.

The Kaishin spent a week sailing north in the Sea of Japan to reach Abashiri Port in the northernmost main island.

The vessel has a compression chamber that can be filled with special gas allowing divers to acclimate themselves for the water pressure around the sunken boat about 120 meters below the sea surface.

If everything goes as planned, the vessel will leave Abashiri Port late in the afternoon of May 18 to head to waters where the tragedy occurred.

If the weather conditions are favorable, divers will start searching the interior of the Kazu I from the morning of May 19 at the earliest. They will begin preparing for salvaging the boat after the search, which will likely take two days.