After a brief debate over what to do with the derelict fishing vessel Ryou-Un Maru, an unoccupied ghost ship that drifted over to U.S. and Canadian waters after being dislodged by last year's tsunami in Japan, the Coast Guard decided sinking it would pose the least risk to other vessels in the shipping route.

Ryou-Un Maru joins a host of other vessels sitting at bottom of the sea in Southeast Alaska, some of which have been explored, others not. How many of those might have also been ghost ships like the Ryou-Un Maru isn't immediately clear, nor is it clear exactly how common such unmanned vessels are.

Petty Officer David Mosley said that the Coast Guard will occasionally respond to such ghost ships.

"We work on occasion with derelict vessels where an owner decides they don't want it anymore, and they let it loose," he said. Such situations "aren't that common, but they're not completely uncommon, either," he said.

The Ryou-Un Maru is a bit more unusual in that it was swept out to sea by the tsunami caused by the massive March 2011 earthquake in Japan, joining a huge patch of trash drifting across the Pacific Ocean that's begun washing up on Canadian and U.S. shores, including in Alaska.

But there's something about ghost ships -- like ghost towns -- that capture the imagination. Perhaps most famous is the tale of the Mary Celeste, which was discovered abandoned in 1872, adrift in the Atlantic Ocean without any sign of its crew and no clues to ever explain what happened to them.

Alaska has a fascinating ghost ship story of its own, one that took place in the high Arctic and was spotted from various regions of the state's northern coastline over the span of 38 years.

The Baychimo was a 1,300-ton cargo and passenger ship operated by the famous Hudson's Bay Trading Company, founded in the 17th century as a fur trading business and eventually growing to encompass transport and travel in waters throughout Canada and the Pacific Northwest.

Baychimo operated 11 years before being abandoned in 1931, lodged in ice not far from Point Barrow, according to the history "Baychimo: Arctic Ghost Ship" by Anthony Dalton. The ship had traveled from Vancouver, B.C., to trade furs with communities along Alaska's Beaufort Sea coast.

After several attempts to rescue the vessel from pack ice, Baychimo was eventually abandoned for the winter, with the thought that the ice tightly packed around the vessel's hull would cause it to sink upon thawing.

That never happened. Instead, the now-unoccupied vessel drifted away, and kept drifting for nearly four decades. It was spotted numerous times in several locations, an eerie, unoccupied vessel adrift in the Arctic Ocean, somehow surviving the regular freezing and thawing of the northern seas.

According to a 1991 Unesco Courier article, the ship began to be spotted all over, including several hundred miles from where it had originally been seen. In 1932, it was spotted by a dog musher who was traveling from remote Herschel Island in the Yukon Territories to Nome. He was even able to board the vessel.

It was boarded again in 1934, this time by the crew of a much smaller trading vessel -- the aptly-named Trader, which regularly traveled the northwestern coastline between Nome and Barrow during Alaska summers. Its crew salvaged goods, including unbolted chairs and ripped mattresses, from inside the derelict Baychimo, according to Dalton.

From then on, the ship was seen numerous times, either from the villages that dot Alaska's coastline or by passing vessels. It was spotted in 1935 and 1939, then many times over the course of the next decades. By the 1960s, many believed it had sunk, but a final report of the Baychimo arrived in 1969. By then, the Baychimo would have been more than 50 years old and adrift without the guiding hand of mariner for nearly 40 years.

The final sighting came during the passage of the icebreaker Manhattan in 1969 as it traveled the Northwest Passage in a bid to examine the feasibility of reaching the remote -- and then-recently discovered -- oil fields of Alaska's North Slope. It was reportedly spotted offshore between Point Barrow and Icy Cape.

It wasn't spotted again after that, and likely finally gave up the ghost and sank to the seafloor somewhere in Arctic waters. Given the sporadic sightings in its later years, who knows where the vessel may have gone down?

A 2006 article in the Ottawa Citizen said that a group of Alaska researchers was attempting to locate the Baychimo -- along with other shipwrecks along the Arctic coast -- as part of a larger seafloor mapping effort. Marine scientist John Kelley was part of that effort, but as of 2012, the project was "ancient history," he said.

Other ghost ships have come and gone since the Baychimo finally disappeared -- one such vessel was even in Alaska waters more recently, when a ship was located more than 250 miles from Attu Island in the Aleutians, adrift and unmanned in 2006. The barge seemed Russian, according to some markings found aboard. It had been adrift for more than five months when discovered, according to a 2006 Anchorage Daily News article. The Coast Guard towed it to Kodiak.