What are U-Boats in World War 2?

Answer 1

German submarines. They were untersee boots (undersea boats).

Britain does not produce enough food to feed its population and must rely on imports to make up the difference. The German Navy was nowhere near powerful enough to challenge to might of the British Royal on the surface. But in both world wars the Germans used U-boats to sink hundreds of cargo ships bound for the United Kingdom, trying to starve the British out of the war and prevent the shipment of war materials.