SM U-12 was a German submarine, built in 1911 and sunk off Scotland in 1915.
It was the first submarine to launch a plane at sea.

U-12 was a Type U 9 U-boat built for the Imperial German Navy.
Her construction was ordered on 15 July 1908 and her keel was laid down by Kaiserliche Werft in Danzig.
She was launched on 6 May 1910 and commissioned on 13 August 1911.

The German Empire was the first nation to experiment with submarine aircraft carriers.
Oberleutnant zur See Friedrich von Arnauld de la Perière of the Naval Air Service and U-12's Kapitanleutnant Walther Forstmann theorised that they could increase the range of their seaplanes by carrying the aircraft out to sea on the deck of submarine and launching the seaplanes after the sub partially submerged, allowing the plane to float off.
SM U-12 was a German submarine, built in 1911 and sunk off Scotland in 1915. It was the first submarine to launch a plane at sea. 
U-12 was a Type U 9 U-boat built for the Imperial German Navy. Her construction was ordered on 15 July 1908 and her keel was laid down by Kaiserliche Werft in Danzig. She was launched on 6 May 1910 and commissioned on 13 August 1911.
The German Empire was the first nation to experiment with submarine aircraft carriers. Oberleutnant zur See Friedrich von Arnauld de la Perière of the Naval Air Service and U-12's Kapitanleutnant Walther Forstmann theorised that they could increase the range of their seaplanes by carrying the aircraft out to sea on the deck of submarine and launching the seaplanes after the sub partially submerged, allowing the plane to float off.
SM U-12 (Germany)