One crew member told the national broadcaster NHK that he had seen a “large white body” on the water’s surface just before the accident. The company said it would open an investigation.

Collisions with marine life have been an occasional problem for ferries in Japan: Whales and other animals are thought to give a wider berth to propeller-driven ships, which are louder than the relatively quiet jetfoils.

In 2016, after a number of accidents involving whales, the local authorities in Kyushu, one of Japan’s main islands — where high-speed ferries are a common mode of transportation — issued new safety requirements for the ships, including having additional padding and requiring all passengers to wear seatbelts, according to reports at the time.