The UB II type submarine was a class of U-boat built during World War I by the German Imperial Navy. They were enlarged from the preceding type UB I and were more effective vessels. The boats were a single hull design with a 50-metre maximum diving depth and a 30-45 second diving time. In 1915 and 1916, 30 were built at two different shipyards.

The Type UB I submarine was a class of small coastal submarines (U-boats) built in Germany at the beginning of the First World War. Twenty boats were constructed, most of which went into service with the German Imperial Navy Boats of this design were also operated by the Austro-Hungarian Navy and the Bulgarian Navy. In the Austro-Hungarian Navy, it was called the U-10 class.