[6] After a long service career the ship's owner decided it was too old for continued use and moored it in Aomori Prefecture in Honshu pending sale.

[citation needed] When the Tōhoku earthquake and tsunami struck in March 2011, Ryou-Un Maru broke free and was set adrift.

[citation needed] For over a year the Ryou-Un Maru drifted across the Pacific as a ghost ship and was carried eastward by the Kuroshio Current.

On 4 April 2012, the U.S. Coast Guard dropped a tracking buoy aboard as the vessel drifted approximately 170 nautical miles (310 km; 200 mi) southwest of Sitka, Alaska.

[5] USCGC Anacapa fired upon it with a Mk 38 25mm autocannon, holing and sinking the Ryou-Un Maru in approximately 1,800-metre (6,000 ft) of water in the Gulf of Alaska 180 miles (290 km) off the coast of the Alaskan Panhandle.