PCU Massachusetts (SSN 798) is a Virginia-class attack submarine.
The Virginia-class, also known as the VA-class or 774-class, is a class of nuclear-powered fast attack submarines in service with the U.S. Navy. The submarines are designed for a broad spectrum of open-ocean and littoral missions. They were conceived as a less expensive alternative to the Seawolf-class attack submarines, designed during the Cold War era, and are replacing older Los Angeles-class submarines, 29 of which have already been decommissioned.