An empty, overturned wooden boat has been found drifting off Japan's western coast, and it could mark the start of another flood of "ghost ships" from North Korea to wash up on Japan's shores.

The vessel, measuring 8-meters (26-feet) long, was found floating in a rocky area off the island of Hokkaido on Wednesday afternoon, Japan's Sankei Shimbun reported.

An unidentified man spotted it while driving around the town of Matsumae-cho around 5:30 p.m. that day.

The Hokkaido Cultural Broadcasting TV station aired a photo of the boat on Thursday:

Although it's not clear where the boat came from, local media has reported town and maritime authorities as saying it could be from North Korea.

Local divers who examined the boat on Thursday morning, which by then had drifted about 50 meters (164 feet) off the Hokkaido coast, reported seeing neither crew members, nor writing, nor symbols indicating where it might come from.

But the shape and colour of the boat found on Wednesday resembled other boats from North Korea that had drifted ashore in the past, the Sankei Shimbun reported, citing town authorities.

One hundred and four "ghost ships" – vessels discovered with no living crew – were found along Japan's shores last year, the highest since authorities started collecting data in 2013. Many were found with dead bodies in them, whlie others were empty.

While Japanese authorities haven't been able to definitively identify the origins of the boats found last year, multiple factors have suggested that they were from North Korea.

A boat found on the island of Sado last November contained what appeared to be North Korean cigarette packets, and jackets with Korean writing on them.

Two bodies recovered from another boat found in Yamagata prefecture in December also wore pins showing the face of Kim Il Sung, the grandfather of Kim Jong Un.

It remains unclear exactly who those people were, or why they showed up in Japan. Experts have posited theories including food insecurity in North Korea, Kim Jong Un's weakening security on his eastern coast, and local fishermen being forced to travel beyond their limits due to annual quotas and a fishing rights deal between North Korea and China.

Japan has been struggling to deal with the remains. Some cities want to send the remains back to North Korea, but that could prove difficult by the lack of diplomatic relations between the two countries.

Jeffrey Kingston, the director of Asian studies at Temple University Japan, has urged caution on determining whether the ship found this week is from North Korea.

North Korea's fishing season typically runs from October to February, he previously told Business Insider, so seeing a vessel in Japanese waters in the summer appears to be an anomaly. The last report of a ghost ship sighting in Japan was this January.

"Much unknown about this case so hard to draw implications," Kingston told Business Insider on Friday.

This article was originally published by Business Insider.

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