A vessel carrying divers trained to work at great depths arrived at a port in eastern Hokkaido on Tuesday in preparation for a search inside a tour boat that sank off the Shiretoko Peninsula last month, leaving 14 people dead and 12 missing.
The vessel, Kaishin, operated by Nippon Salvage, is slated to leave Abashiri port late Wednesday afternoon. The divers are expected to start searching inside the 19-ton Kazu I, located about 120 meters below the surface, as early as Thursday for anyone left inside.
Underwater drones have already been used to search inside the boat, but no one was found.
The divers will attempt a special technique known as saturation diving, in which they absorb a mix of oxygen and helium so they can adjust their bodies to the level of water pressure at the depth they intend to work at.
The transport ministry's Hokkaido bureau conducted an on-site inspection of four tour boat operators in the town of Shari on Tuesday to check their safety practices. The Kazu I was based there.
Shiretoko Yuransen, the boat's operator, has already undergone a special audit by the ministry.
Japan Coast Guard boats continue to search for the missing at sea, while police have expanded their search to areas south of the peninsula.
The tour boat was carrying 24 passengers and two crew members when it made a distress call and disappeared on April 23 after leaving Utoro port in Shari for sightseeing along the scenic peninsula, despite a forecast for rough weather.