U.S. Navy's Unmanned Surface Vessel Completes Fastest Transatlantic Crossing

A U.S. Navy-sponsored unmanned surface vessel has completed the fastest known autonomous transatlantic crossing, arriving in Troia, Portugal, on Sept. 9 after more than two months at sea.

Engineers from the Naval Information Warfare Center (NIWC) Atlantic’s Unmanned Naval Innovation Team (UNIT) recovered the solar-powered Lightfish after its 4,000-mile journey, which began in late June from Sullivan’s Island, South Carolina. The vessel completed the voyage nearly 12 days faster than the last known attempt.

Lightfish remained untouched for more than 60 days as it crossed the Atlantic. Engineers and fleet watch floors monitored the vessel through cameras, remote software and real-time telemetry. Michael Grass, the team's lead scientist and program manager, said the mission validated a “follow-the-sun” command-and-control model, with oversight transferred twice daily between Navy numbered fleets.

The operation was supported by Commander, Task Force 66 (CTF 66), U.S. 6th Fleet’s all-domain task force formed in 2024. The recovery aligned with the Portuguese-led Robotic Experimentation and Prototyping using Maritime Uncrewed Systems (REPMUS) exercise, which gathers more than 30 nations, NATO organizations, industry and academic partners to test unmanned systems.

After arriving in Portugal, Lightfish required minor repairs, generator fuel and cleaning. Engineers scraped barnacles from its hull after the long crossing and several days spent loitering offshore.

Lightfish will remain at sea for additional missions, including travel to Africa and a future return crossing to Charleston. UNIT engineers will use the deployments to refine autonomy, endurance and data-integration capabilities.