I have seen many comments on this thread on how this could have happened, but as a 7th Fleet Sailors station out of Yokosuka, I can tell you that the waters 50 miles outside of the port of Tokyo is a friggin park lots full of containment ships coming and going!
These containment ship Captains and crews of many nations are some of the worst sea drivers on the planet. I have seen these idiots race each other in the Persian Gulf and the Suez Canal. Even in Singapore, they had us anchor a mile away from these ships, so I can understand how this even happened.
In the straights of Gibraltar the CO just forgot the radar and we went through visually. It is amazing more ship don’t collide.