The $2.6 billion USS South Dakota (SSN 790), seen here in a photo illustration, is the newest, most-advanced addition to the US Navy's Virginia-class fleet of nuclear-powered, fast-attack submarines. The South Dakota was commissioned in February 2019 as the Navy's 17th Virginia-class submarine; the Navy hopes to have 66 Virginia-class subs by 2048.
Here's everything we know about the South Dakota and other Virginia-class subs, including the USS Delaware (SSN 791), the next addition to the fleet, which is expected to begin active service this year.
The 377-foot-long , 7,800-ton South Dakota was christened on Oct. 14, 2017, at the Groton, Conn., shipyard of its builder, General Dynamics Electric Boat.
The South Dakota is powered by a S9G nuclear reactor that will provide all the fuel the boat will need during its projected service life of 33 years.
A videotaped walking tour of the pre-commissioned South Dakota in November 2018 shows the corridors that the 135-person crew work in as the boat takes on missions in shallow waters -- or dives to depths of more than 800 feet.
The South Dakota, seen at the conclusion of its commissioning ceremony, is considered the stealthiest Virginia-class submarine yet -- the lead vessel, per The National Interest, in the Navy's "acoustic superiority program."
During the November 2018 walking tour of the pre-commissioned South Dakota, a sailor adjusts a remote actuator. On Virginia-class subs, actuators control a variety of tasks, including torpedo-launch sequence.
The South Dakota, like other Virginia-class submarines, including the USS California (SSN 781), is equipped with four MK-48 launch tubes. Here the California during an ordnance-loading exercise.
This is another look from the ordnance-loading exercise on the USS California. Here, crew members perform final checks on an inert MK-48.
A shipbuilder works on one of the Delaware's four torpedo tubes.
The Tomahawk Land Attack Missile, seen here in a controlled test flight conducted by the US Navy, is another part of the Virginia-class submarine's arsenal. Each sub is capable of launching 12.
The USS North Dakota (SSN 784), seen here during a pre-commissioning sea trial, was the first boat produced from the third wave, or Block III, of the Navy's Virginia-class-sub orders.
As a Block III Virginia-class sub, the North Dakota features a simplified design that allows its Tomahawk missiles to be launched from two payload tubes, instead of 12 individual tubes, as is the case in the older, Block I- and Block II-era subs.
The Delaware, seen here being touted at a 2012 Pentagon press conference attended by then-Vice President Joe Biden and his wife, Jill Biden. The Delaware is the Navy's eighth -- and last -- Block III sub.
The pressure hull on the USS Delaware was completed in Virginia in September 2018. The boat was launched about three months later.
This is the USS California (SSN 781), the eighth Virginia-class sub, as it appeared in 2010 when work on its pressure hull was completed.
Secretary of Energy Rick Perry, left, visits the control room of the USS John Warner (SSN 785), the 12th Virginia-class submarine, in November 2018.
Here are display screens in the control room of the USS Illinois (SSN 786), the 13th Virginia-class submarine. Like other subs in its class, the Illinois doesn't have a periscope. Instead, it's guided with the help of photonic-mast sensors that send images to the control room.
Sailors in the South Dakota galley -- or Wild Bill's Bistro, as the kitchen's been dubbed -- prepare meals for the pre-commissioning crew during the 2018 videotaped walk-through.
Here's a more detailed view of a galley on a Virginia-class sub. This galley is found on the USS Washington (SSN 787), which was commissioned in 2017.
In January 2019, one month before the commissioning ceremony that puts the boat into active service, the South Dakota is seen on Connecticut's Thames River.
The USS Indiana (SSN 789) is the 16th Virginia-class submarine. Commissioned in September 2018, it's seen here during a pre-commission run.
The Indiana's supply officer handles business from his berth during a pre-commission run in the Atlantic Ocean in June 2018.
The bridge team from Indiana's pre-commissioning crew stands watch as the sub enters Port Canaveral, Florida, the location where the vessel was eventually commissioned.
Machinists aboard the pre-commissioned, Virginia-class USS Colorado (SSN 788) perform a weapons check on a Mark 48, or Mk 48, a light machine gun also known as a "super SAW," for squad automatic weapon.
Here's a rescue exercise involving the Navy's Undersea Rescue Command (URC) and the USS Texas (SSN 775), the second Virginia-class sub. A URC commander climbs from a rescue module into the escape hatch of the Texas.
A member of the naval color guard raises the admiral's flag during the commissioning of the South Dakota on Feb. 2, 2019, at the Naval Submarine Base New London in Groton, Conn.
At the 2019 commissioning ceremony, the South Dakota crew stands ready to assume official duty.
Part of a naval commissioning is the ceremonial passing of the long glass, or telescope. Here, a veteran who served aboard the World War II-era battleship USS South Dakota (BB 57) hands the scope to an officer on the USS South Dakota (SSN 790). The new sub is the Navy's third vessel named for the state of South Dakota.
A system check is performed on the Colorado's weapons-launch console in January 2018. The Colorado was commissioned as the Navy's 15th Virginia-class sub in March 2018.
In 2016, on the dry land of Denver's Brown Palace Hotel, two Navy seamen from the pre-commissioned USS Colorado get tips from chef Michael Wright on Colorado favorites, such as Rocky Mountain trout.
This is a shot of the only washing machine and only clothes dryer aboard the Virginia-class USS Washington (SSN 787). Like the other Virginia-class subs, the Washington, commissioned in 2017, boasts a crew of about 135.
Reportedly, there are more crew members (130-plus) than beds (about 90) in Virginia-class submarines. In this shot from June 2018, sailors catch Zs in temporary racks in the torpedo room of the pre-commissioned USS Indiana (SSN 789).
Sailors dine on the pre-commissioned USS Indiana in June 2018. On Virginia-class subs, three meals are prepared daily; prep work on each meal begins four hours in advance.
A decked-out Colorado sits at the pier of the Naval Submarine Base New London in Groton, Conn., on the day of its commissioning, March 17, 2018. The sub is the 15th Virginia-class vessel.
Here's a close-up view of a passageway from the Virginia-class USS Colorado.
In 2018, a 7-year-old boy greets his sailor father upon the return of the USS Virginia (SSN 774) from the European Command Area of Responsibility to the boat's Connecticut home port.
The is the 1999 keel-laying for the Virginia, the original Virginia-class submarine. The Virginia-class boats are intended to replace the Navy's smaller, older Los Angeles-class submarines.
In 2014, the USS John Warner is moved to a floating dry dock in advance of its christening in Newport News, Virginia. According to the Navy, it took shipbuilders eight hours to move the boat from its assembly facility to the dock.
The USS Indiana is seen on the day of its commissioning in Port Canaveral, Florida, on Sept. 29, 2018.
During the 2012 commissioning ceremony of the USS Mississippi, the ninth Virginia-class submarine, sailors heed the new boat's first official order to "man the ship."