UB-116 is a candidate for the final naval action of World War I

What was the last naval action of World War I?

The sinking of UB-116 is a strong possibility, although shore bombardments continued close to the armistice and make a definitive answer difficult.

The last action remains unsettled because shore bombardment continued almost until the armistice. The answer depends on what counts as an action and on exact timing. The destruction of UB-116 is one of the latest strong candidates, but incomplete operational chronology prevents a definitive choice.