A Submarine is a fleet of Tau'ri watercraft that can operate independently below water, as distinct from a submersible that has only limited underwater capability.
In 2000, a Replicator-controlled Biliskner crashed into a Russian submarine, where the Replicators soon took control of it. The USS Dallas destroyed the Replicator incursion. (SG1: "Small Victories")
During World War II, German submarines were called U-boats. (SG1: "Continuum")