Japan’s coastguard said on Sunday that at least 10 of the 26 people aboard a tour boat that went missing off the northern island of Hokkaido have been confirmed dead, while the search for the others was continuing. The coastguard launched a rescue operation on Saturday after the 19-tonne <i>Kazu 1</i> sent a distress call saying its bow had flooded and that it was beginning to sink and tilt, while travelling off the western coast of Hokkaido's Shiretoko Peninsula. The boat had two crew members and 24 passengers aboard, including two children. None were found until Sunday morning. The Transport Ministry, meanwhile, launched an investigation into the boat’s operator over its safety standards and decision to conduct the tour despite rough weather. “We will thoroughly investigate what caused this situation and what kind of safety oversight was involved to allow the tour in order to prevent another accident,” said Transport Minister Tetsuo Saito, who visited the area on Sunday. The ministry will also investigate if or how Saturday’s accident was related to two previous accidents involving the same boat last year, Mr Saito said. The operator had been instructed to take steps to improve its safety following the incidents. The coastguard confirmed that the same boat capsized in the area last June, although nobody was injured. In May, the boat collided with an object at sea, causing minor injuries to three passengers. An official for the vessel’s operator, Shiretoko Pleasure Cruise, declined to comment, saying he had to respond to calls from worried families of the passengers. The coastguard reported finding nine people earlier on Sunday after the rescuers intensified their search. All of them were found near the tip of the peninsula, north of where the boat sent a distress call. The location is known as a difficult place to manoeuvre boats because of its rocky coastline. The coastguard initially said it could not confirm whether they were rescued alive. NHK public television said they were unconscious. Footage on NHK showed one of the rescued people arriving on a helicopter and being transferred to an ambulance on a stretcher, while rescuers held up blue plastic shields for privacy. An orange-coloured, square-shaped life-saving float with the boat’s name on it was also seen on the rocky coast. The first reported rescue on Sunday came after nearly 19 hours of intense search involving six patrol boats, several aircraft and divers. The search continued through the night and was expanded with local fishing and tour boats joining the efforts, while Japan's Self Defence Force sent a destroyer and three planes. The coastguard said they were told that everyone on board was wearing a life jacket. However, average April sea temperatures in Shiretoko National Park are just above freezing, greatly reducing the chances of survival. The cause of the accident is still under investigation, but experts suspect there may be a safety negligence, and the boat ran aground and was damaged in rough seas in an area known for strong currents and a rocky coastline. High waves and strong winds were reported in the area around noon on Saturday, according to a local fisheries co-operative. Japanese media reports said fishing boats had returned to port before noon because of the bad weather. NHK said there was a warning for high waves of up to three metres. A tour boat crew belonging to another operator told NHK that he warned of rough seas when he spotted the <i>Kazu 1</i> crew and told them not to continue the trip. Yoshihiko Yamada, a Tokai University marine science professor, said the boat was likely to have capsized after it was tossed around in high waves and damaged, flooded and probably sank. A tour boat of that size usually does not carry a lifeboat, and passengers possibly could not escape a rapidly sinking vessel with its windows likely to have been closed to shield them from strong winds. In an interview with TBS television, the professor said there was also a slight possibility the boat could have been hit by a whale. According to the operator’s website, a tour takes around three hours and offers scenic views of the western coast of the peninsula and includes potential sightings of animals such as whales, dolphins and brown bears. The national park is listed as a Unesco World Heritage site and is famous as the southernmost region to see drifting sea ice.