Search and rescue operations continue in northern Japan after a tour boat disappeared on Saturday. But rough seas made it difficult on Wednesday.

The 19-ton "KAZU I" went missing off the coast of Hokkaido. It was carrying 24 passengers and two crew members. 11 are dead, and 15 are still missing. The ship set sail despite gale and high wave advisories.

Coast Guard officials have yet to find the ship or more of the missing people.

They received a report from a fishing boat on Tuesday saying its fish-finding equipment had detected a large object at a depth of 30 meters. But divers only found rocks on the seabed.

Strong winds and rough seas are pummeling the coast. Small-sized vessels, including local fishing boats, were unable to join Wednesday's rescue operation.

The cruise ship operator's president apologized for the accident at a news conference.

President Katsurada Seiichi of Shiretoko Pleasure Cruiser said, "I am truly sorry for the victims and for the people who are still missing."

Katsurada said the captain of the ship told him on Saturday morning it was possible to operate the 10 a.m. cruise although the weather could turn harsh in the afternoon. He said he decided to allow the captain to sail, on the condition he would return if the sea became rough.

The president also said he learned shortly after the conversation that a radio communication antenna at his company was broken.

But he decided not to cancel the cruise because his staff were able to use cell phones.

He also said the ship could contact other cruise companies, who could relay messages.

Coast Guard officials are looking into whether the boat operator had proper safety measures in place.