HII has completed the base-year production of its Lionfish small unmanned underwater vehicle (UUV) for the US Navy, marking a key milestone in the service’s effort to expand autonomous undersea warfare capabilities. The contract, awarded in 2023, is focused on meeting “critical undersea warfare needs” as the Navy integrates uncrewed systems alongside manned platforms, including Virginia-class attack submarines.
The company completed the production of 42 Lionfish hulls in December, following the delivery of the first two units in April 2025. Manufacturing and integration work is being conducted at HII’s facility in Pocasset, Massachusetts. Under the program structure, HII is expected to continue building the system for the Navy through 2028, with options that could expand the fleet to as many as 200 vehicles.
Lionfish is derived from HII’s Remus 300 autonomous underwater vehicle, which features an open-architecture design to support future payloads and mission upgrades. Depending on configuration, the Remus 300 measures approximately 3 meters in length and weighs around 70 kilograms, offering a compact yet capable platform for undersea operations.
Performance specifications include a range of up to 165 kilometers, a cruising speed of 5 knots, and an operational depth of 1,000 feet. The system can be recharged in 6 to 18 hours, enabling rapid redeployment. The US Navy selected the Remus 300 for the Lionfish program in 2022, replacing the legacy Swordfish UUV, which was based on the earlier Remus 100 platform.
