TOKYO, Japan – Japanese rescuers on Monday confirmed the death of a child in a weekend sightseeing boat accident, raising the death toll to at least 11, as efforts to find survivors continued.

The Kazu I was carrying 24 passengers, including two children and two crew, when it sent a distress signal on Saturday afternoon as it began to take on water in the frigid waters off Japan's northern Hokkaido island.

Ten people were recovered and confirmed dead by early Sunday evening, and the coast guard said it retrieved a child later that night, whose death was confirmed on Monday morning.

The boat sent a distress signal from off the coast of the Shiretoko Peninsula, prompting the launch of a search-and-rescue operation.

But the remote location and poor conditions meant it took several hours for coast guard vessels and aircrafts to arrive on the scene.

All those on board were reportedly wearing life jackets, but hopes for survivors faded quickly given the icy temperatures in the region, with the water estimated to be around two or three degrees Celsius (36 or 37 degrees Fahrenheit).

The boat had set out on Saturday morning on a sightseeing cruise of the sort that is popular in the Shiretoko Peninsula, a designated UNESCO World Heritage site for its pristine natural environment and diverse wildlife.

The tour went ahead despite high winds and waves that reportedly prompted some local fishing boats to return to shore to avoid the worsening conditions.

Japan's Self-Defense Forces and police, as well as some local fishing boats, were assisting in the search operation, with local media saying bodies had been retrieved from both the water and coast.

The transport ministry has sent officials to the company that operated the sightseeing boat to determine whether they were operating within safety guidelines, and to investigate the cause of the accident, a ministry spokesman told AFP.

Rescue operations were delayed in part by rough seas that meant the first boats did not arrive on the scene until more than four hours after the distress signal was sent, a government spokesman said.

The aircraft closest to the site was out on patrol at the time, and had to refuel and pick up divers before it headed to the site, also creating delays, he added.

- 'Praying for their safety' -

Those killed in the accident have not yet been identified, though officials said they included seven men and three women, in addition to the child.

A man whose parents and brother were on the boat told the Mainichi Shimbun newspaper that he had given them the tour as a present.

"They may still be in the cold sea, but I'm praying for their safety," he told the newspaper.

"I want to find out what happened to them as soon as possible, but I don't know what to do," he added.

And the father of a passenger said his 22-year-old son had taken the trip with his girlfriend and had planned to propose.

"I learned that my son brought a ring and decided to propose to her on the trip as a surprise," Tsuyoshi Suzuki told local station Hokkaido Broadcasting.

"I talked to her parents last night, crying. We discussed how we really hope they come out of this together, not separately," he said.

"I know there is no hope, but I just want them to be found together."

The Kazu I ran aground in shallow water in June last year, but was able to free itself and return to port, where its captain was subsequently investigated for endangering traffic by negligence in the conduct of business.