US Navy's new Virginia-Class submarine USS Massachusetts passes key sea trials.

The U.S. Navy’s Virginia-class attack submarine USS Massachusetts (SSN 798) completed its first sea trials off the Atlantic coast in early October 2025 under US Navy and Huntington Ingalls supervision. The evaluations verified propulsion, submergence, and combat systems ahead of formal delivery scheduled for spring 2026.

Huntington Ingalls Industries’ Newport News Shipbuilding division confirmed that the U.S. Navy’s Virginia-class submarine USS Massachusetts (SSN 798) completed its initial sea trials in the Atlantic Ocean on October 7, 2025. The trials included the submarine’s first submergence, high-speed runs, and systems checks conducted jointly by Navy and shipyard test teams. Delivery of the Block IV submarine is planned for spring 2026, following additional inspections and acceptance testing.
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The USS Massachusetts will be the 12th Virginia-class submarine constructed and delivered by Newport News Shipbuilding, one of only two U.S. shipyards capable of building nuclear-powered submarines. (Picture source: HII)

Conducted over several days at sea, the trials included the USS Massachusetts’s first submergence, surface and submerged high-speed maneuvers, and systems verification under the supervision of the Newport News and Navy test teams. These evaluations mark a key phase before the submarine’s formal delivery to the U.S. Navy, expected in spring 2026. The USS Massachusetts is the 25th Virginia-class submarine constructed and will be the 12th delivered by Newport News Shipbuilding, one of only two U.S. shipyards capable of building nuclear-powered submarines. The company confirmed that post-trial inspections and further testing will continue before commissioning, which is planned to take place in Boston at the Port of Boston’s Conley Terminal, pending Navy approval.

The construction of the USS Massachusetts began after its order on April 28, 2014, as part of the U.S. Navy’s $17.6 billion contract for ten Block IV Virginia-class submarines awarded to General Dynamics Electric Boat and Huntington Ingalls Industries. Its keel was laid down on December 11, 2020, in a virtual ceremony due to the COVID-19 pandemic, before being christened by sponsor Sheryl Sandberg on May 6, 2023, and launched on February 23, 2024. The submarine reached pressure-hull completion in August 2022, marking the joining of all hull sections into a single watertight unit before launch. Following its christening and launch, the submarine began harbor and pier testing before the initial sea trials were confirmed on October 7, 2025. The USS Massachusetts honors the Commonwealth of Massachusetts and continues a lineage last represented by the battleship USS Massachusetts (BB-59), which was decommissioned in 1947 and now serves as a museum ship at Battleship Cove in Fall River.

The Block IV configuration of the Virginia-class, to which the USS Massachusetts belongs, introduces several lifecycle optimizations designed to enhance operational availability while minimizing long-term maintenance requirements. Earlier Virginia-class submarines required four major depot availabilities throughout their service lives, while the Block IV design reduces that number to three, allowing each boat to achieve up to fifteen operational deployments across an estimated 33-year core life. These changes are based on extending the lifespan of critical components and refining subsystem maintenance schedules. Each Block IV submarine, including the USS Massachusetts, integrates two large Virginia Payload Tubes (VPTs) that can each launch up to six Tomahawk BGM-109 cruise missiles through Multiple All-Up Round Canisters, replacing the earlier arrangement of twelve individual launch tubes. The submarines maintain a standard complement of 135 personnel, comprising 15 officers and 120 enlisted crew members organized into engineering, weapons, navigation, and supply departments.

In addition, the USS Massachusetts retains the key dimensions and performance parameters of the Virginia-class, with a length of 377 feet (115 meters), a beam of 34 feet (10.4 meters), and a displacement of approximately 7,800 tons (7,925 metric tons) when submerged. It is powered by the S9G pressurized water nuclear reactor coupled with steam turbines and a pump-jet propulsor, providing more than 40,000 shaft horsepower and a top speed exceeding 25 knots. The reactor allows continuous operation limited primarily by crew endurance and resupply requirements, enabling the submarine to remain submerged for up to three months. The test depth exceeds 800 feet, consistent with class norms. Its armament includes four 533 mm torpedo tubes capable of launching Mk 48 heavyweight torpedoes, as well as twelve vertically launched Tomahawk cruise missiles housed within the two payload tubes. These capabilities allow the USS Massachusetts to conduct precision strikes, intelligence gathering, surveillance, reconnaissance, anti-surface and anti-submarine warfare, and special operations support.

The Block IV upgrade maintains the general layout of preceding Virginia-class submarines but incorporates mechanical and software updates intended to simplify maintenance and reduce life-cycle costs. The class uses photonics masts instead of traditional optical periscopes, employing high-resolution imaging, infrared, and laser rangefinder systems to relay visual data to digital control consoles within the command center. This eliminates the need for direct hull penetration, improving safety and allowing flexible control room placement. The sonar system uses the Large Aperture Bow (LAB) array, wide-aperture flank arrays, and towed arrays to detect, track, and classify underwater targets across multiple frequency bands. The submarines are also equipped with a lock-in and lock-out chamber that enables deployment of divers and special operations forces while submerged. Newport News and General Dynamics Electric Boat jointly construct these submarines, alternating production responsibilities between modules such as the bow, reactor compartment, and stern to ensure production continuity and maintain industrial expertise across both facilities.

As a Block IV submarine, the USS Massachusetts does not feature the Virginia Payload Module (VPM) that will be introduced beginning with the second Block V submarine, the USS Arizona (SSN 803). The VPM adds a mid-body section containing four additional large-diameter payload tubes capable of launching up to 28 Tomahawk missiles, significantly increasing total missile capacity from 37 to approximately 65. However, Block IV units like the USS Massachusetts bridge the design evolution between earlier configurations and these enhanced variants, maintaining the same hull length, displacement, and propulsion plant while integrating minor structural adjustments to improve maintainability and availability. The submarine’s operational life is projected to extend beyond 2058, aligning with the US Navy’s broader goal of maintaining a fleet of at least 66 nuclear-powered attack submarines to sustain global undersea operations.

With 24 units already in service, the Virginia-class now represents the cornerstone of the U.S. Navy’s undersea warfare strategy; it combines the stealth required for covert intelligence collection and precision strike missions with the endurance and flexibility needed to operate in both deep-ocean and littoral environments. The class replaces the Los Angeles-class attack submarines while bridging toward future programs like the SSN(X), ensuring that U.S. naval forces retain credible sea-denial and power-projection capabilities worldwide. Each submarine can independently execute surveillance, special operations insertion, and strike tasks without a reliance on surface assets, giving the US Navy a persistent and survivable deterrent option. With the ability to integrate future payloads and unmanned systems, the Virginia-class remains central to maintaining freedom of action beneath contested waters and supporting broader joint-force operations through intelligence gathering, targeting, and long-range strike functions.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.