On a route in traffic separation in the southern Baltic Sea, a sudden sharp impact was noticed on the ship. Something had passed through the hull in the fore and came up through the rear deck, causing a hole with a diameter of approximately one metre. The crew could not understand the reason behind the incident and went to port for further investigation and a seaworthiness inspection. The conclusion later was that it was most likely a jack-up leg that caused the damage. A tug boat that had passed by shortly before had dropped one.