BEFORE SUBMARINES can stealthily do their jobs below the waves, they must start their lives on land. The Virginia class is America's newest nuclear-powered attack submarine, also known by SSN-774. It is a group of 377-foot-long underwater ships. Their mission? Their mission is to conduct surveillance, fight other ships, and occasionally, launch conventional cruise missiles at land targets if necessary. Their maximum depth of diving? It's a mystery. Their top speed? Ditto.

We know that these submersibles will provide protection for a number of sailors from the sea's immense pressure. This is in addition to the nuclear reactor within the submarine, which powers everything by heating water into steam and powering the propulsion system. Electric Boat workers, an arm from General Dynamics that is responsible for many of these vessels' construction, know that craftsmanship is more than just a matter to be proud of. One mistake in their precise metalworking could spell doom for the vessel in the deepest depths. These subs, also known as boats, are assembled at Quonset Point, Rhode Island and Groton in Connecticut.

It can go deeper than 800 feet and the pressure will exceed 300 pounds per square inch. This massive machine uses thousands of tons of force and pressure to bend the thick steel, but its exact width remains a mystery. The press bends the material slightly more than is necessary to ensure it springs back into its desired crescent.

These plates must be cut to a certain length. The way they are trimmed also matters. Each piece of bent plate should have a precise bevel shape to allow it to join with its neighbor. Soon, multiple sections will be joined to create huge ring-shaped segments for the futur submarine.

Robots and humans join the bent plates to make 34-foot-wide rings, which will eventually be stacked into the hull. To create rib-like supports, they'll also fuse I beams to the interior. The hull should be perfectly round to ensure strength. A circle will withstand all pressures.

The reinforced cylinder is scaffolded so that welders can complete their jobs, such as attaching brackets and pipe hangers to other elements. If the section was prone, as it is now in its final form, the workers would need to complete their tasks on the floor or lying down.

It doesn't matter if the seam is in the hull or another component; it's important that this work is done correctly. Electric Boat uses nondestructive methods, such as X-rays and dye tests.

These sections are built by shipbuilders on the shop floor. They then slide them into larger pieces of the sub--as though slipping a ship into a bottle. Electric Boat claims this is three times faster than building within one hull cylinder.

Seafarers may have to share racks during jammed missions.

This piece of hardware will be used in the interior of the submarine, which is made up of a variety metals. The stainless steel bathrooms and food preparation areas are protected from rust. Workers also inspect for any potential mold or bacteria growth. Aluminum and other materials are suitable for places where strength is not essential, such as a locker door.

These segments will be ready for shipping on a barge between Quonset Point and Groton when they are complete. Each one will be completed at least 90 percent by then. They will be joined with other segments in Groton. This step is also required for equipment for the engine room or other large components.

This gearing is part of the so-called dogging mechanism. To lock a hatch, turn the wheel. This machinery gives the entryway the same structural integrity that every other part of the hull.

The "sail", the vessel's distinctive peak, holds sensor-filled antennas called masts. These masts replace old-school periscopes and other equipment. The vessel still needs an official name. It is known as a pre-commissioning unit (or PCU) until it receives Navy ship.

This story first appeared in PopSci's Summer 2022 Metal issue. See more PopSci+ stories.