On May 15, 2025, the Royal Navy officially unveiled its first extra-large uncrewed underwater vehicle (XLUUV), now formally designated XV EXCALIBUR. This milestone marks a significant development in the global evolution of underwater drone capabilities—EXCALIBUR is also the first XLUUV to be introduced by a European navy.

The prefix XV, standing for eXperimental Vessel, reflects the system’s role as a technology demonstrator. EXCALIBUR is the tangible outcome of the CETUS project, an experimental initiative launched in 2022 by the Royal Navy's technical branches dedicated to the assessment of uncrewed systems and emerging naval technologies. Constructed by MSubs in Plymouth and launched for the first time in February, the vehicle measures 12 meters in length, 2.2 meters in diameter, and displaces 19 tonnes. Over the past few months, EXCALIBUR has undergone a series of shore-based and at-sea acceptance trials in the Devonport area.

As a technology demonstrator, EXCALIBUR is not an operational asset per se, but it is designed to explore the potential of XLUUVs to perform a range of underwater missions. These include intelligence, surveillance, and reconnaissance (ISR)—even in deep waters—as well as the deployment of sensors and other payloads (including in denied or contested environments), and even kinetic actions against potential threats. The drone will be assigned to the Royal Navy’s newly established Fleet Experimentation Squadron, managed by the Disruptive Capabilities and Technologies Office, and will operate alongside XV PATRICK BLACKETT, the surface experimentation platform already in service for testing cutting-edge naval technologies.

Imagery released during the unveiling shows the British XLUUV featuring X-shaped control surfaces, a three-blade propeller, and what appears to be a telescopic mast, likely for communications and surface-level observation. EXCALIBUR’s large size offers significantly greater autonomy and payload capacity compared to smaller uncrewed underwater vehicles, while its modular architecture allows for flexible mission configuration—underscoring its inherent multi-role potential.

The May 15 ceremony was attended by representatives from the AUKUS nations—Australia, the United States, and the United Kingdom—with Canberra and Washington likely interested in evaluating the platform for potential use in the Indo-Pacific theater. Notably, EXCALIBUR is comparable in size to the U.S. Navy’s ORCA XLUUV, which is approximately 15 meters long in its baseline configuration. It is also similar to the Chinese XLUUV recently spotted aboard a tug.

Follow us on Telegram, Facebook and X.