The Type XXI was a German submarine developed during World War II, known for its advanced design and capabilities. It was the first submarine to be built with the ability to operate primarily underwater, featuring a streamlined hull and powerful electric motors that allowed for longer submerged travel compared to earlier models. This submarine was equipped with a snorkel, enabling it to recharge its batteries while remaining mostly submerged. The Type XXI represented a significant technological advancement in submarine warfare, influencing post-war submarine designs and contributing to the evolution of modern submarines.