Submarine fleets are groups of submarines operated by a navy or military organization. These fleets are designed for various purposes, including defense, surveillance, and strategic deterrence. Submarines can be equipped with advanced technology, allowing them to operate stealthily underwater and carry out missions without being detected. Countries maintain submarine fleets to enhance their naval capabilities and protect their interests. Notable examples include the United States Navy and the Russian Navy, both of which have invested heavily in modern submarines. These fleets play a crucial role in maintaining national security and conducting underwater operations.