Probably got a near miss from a ship. I know from personal experience that the ships are sometimes piloted by other personnel. After the captain or first mate goes to sleep.
We had a near miss on our offshore drilling rig back in 1995, off of Corpus Christi. In the middle of the night a freighter came close enough to us that we could have used the crane (150ft boom) to offload him.
Now this rig was 234ft x 234ft square and 80ft out of the water, not including a 150 tower on top. You can't see with your eyes closed!