bono,
Right. A container comes off the ship at less than 32.5 tons, and as long as the nature of the contents only allow it take on about 38 tons of water, it'll remain a menace to shipping. If it takes on more, then it goes to the bottom.
If the size of 24m is correct, then it's too big to be a container.
I assume that several containers were found during the search for objects.