MathsShare

This answer is open to debate - but is my personal view of the situation.

When the container is on the ship it is displacing its own weight of water (the ship and the container are both floating). When the container slips off the ship, the container sinks because it is unable to displace its own weight of water. Hence it is displacing less water. (It is displacing its volume.)

Thus less water is displaced - so the height of the water will be lower.