A giant white cylinder has been found floating around in the East China Sea near Nagasaki Prefecture:

The plastic-coated steel cylinder, which measures three to four meters in diameter and is marked “Nitrogen-filled,” “Warning” and “Vacuum” in both Chinese and English, was first spotted by a fishing boat that was sailing in the area.

The Nagasaki Coast Guard Office is trying to identify the cylinder, and believe it may have been accidentally dropped from a large vessel that was transporting machine parts.

Update: The Coast Guard has confirmed that the container was from a Chinese ship.