The Hvalen incident was a short and small-scale confrontation between the navies of Sweden and Germany as a consequence of the First World War.

At 6:15 am on the 21 of October 1915, the Swedish submarine Hvalen departed from Ystad under captain B. Zander to patrol the waters of Øresund, she was shortly thereafter joined by the escort boat Blenda.

[3] The light bomb was met with confusion by the crew of Hvalen who thought that it was some sort of signal to the other auxiliary cruisers and therefore simply slowed down to avoid it.

By the time the eighth projectile had been fired, the German gunner Kreuger noted that the ship's cannon was no longer functional.

However, while on their way to ram Hvalen, the Germans eventually spotted the Swedish flag when they had come within a couple of hundred meters of the submarine.