The Type UC I coastal submarines were a class of small minelaying U-boats built in Germany during the early part of World War I. They were the first operational minelaying submarines in the world (although the Russian submarine Krab was laid down earlier). A total of fifteen boats were built. The class is sometimes also referred to as the UC-1 class after SM UC-1, the class leader. The Italian X-class submarine was a reverse-engineered and modified type of the UC-1-class.