HII has completed the final base-year production phase of the Lionfish small unmanned underwater vehicle for the US Navy, advancing the service’s move toward expanded autonomous undersea operations.
Awarded in 2023, the Lionfish program addresses critical undersea warfare needs as the Navy fields autonomous systems to operate alongside crewed platforms such as Virginia-class attack submarines. HII completed 42 hulls by December, following the delivery of two units earlier in April 2025.
The company plans to continue Lionfish production through 2028, with options in place for the Navy to procure as many as 200 vehicles. Associated manufacturing and program support activities are being conducted at HII’s Pocasset, Massachusetts facility.
The Lionfish is based on HII’s Remus 300 underwater drone, a modular, open-architecture platform designed for adaptability and future capability growth. In its standard configuration, the Remus 300 measures roughly 3 meters in length and weighs approximately 70 kilograms.
Performance characteristics include a range of up to 165 kilometers, a maximum speed of about 5 knots, an operating depth of up to 1,000 feet, and a recharge cycle lasting between 6 and 18 hours.
The US Navy selected the Remus 300 for the Lionfish program in 2022 following a competitive evaluation, replacing the legacy Swordfish UUV fleet derived from the earlier Remus 100 system.
