Concrete ships sound like a contradiction, but the engineering was sound enough. Reinforced with steel rebar and shaped into a proper hull, concrete could float by the same physics that keeps any vessel afloat: displace more water than the weight of the structure, and buoyancy does the rest. The Atlantus completed her sea trials with a 400 to 500-mile shakedown voyage and made her maiden run to Wilmington, Delaware, on May 26, 1919. The Liberty Ship Building Company, headquartered in Wilmington, had designed her for service between New York and the West Indies. She made seventeen voyages before the economics caught up. Concrete ships were heavy, slow, and expensive to operate. The Atlantus was laid up at Norfolk and left to rust, or rather, to crack.

In 1926, Colonel Jesse Rosenfeld saw an opportunity. He purchased the Atlantus and two of her concrete sister ships to serve as the foundation for a ferry dock at Cape May. The plan was audacious: dig a channel to shore, sink the Atlantus in place, and position her sisters in a Y formation to create a sheltered slip where ferries could dock. It was the kind of plan that works beautifully on paper. Groundbreaking ceremonies were held in March 1926. The Atlantus was repaired and towed south to Cape May. Then, on June 8, a storm rolled in. The ship broke free of her moorings and drifted 150 feet off the coast of Sunset Beach, where she ran aground on a sandbar. Several attempts to free her failed. Colonel Rosenfeld's ferry terminal was never completed.

The stranded hulk became an accidental landmark. The Coast Guard base at nearby Sewell Point used the wreck for breeches buoy training, firing rescue lines to the grounded ship as practice for saving sailors from real wrecks. Someone painted a billboard on her exposed side advertising boat insurance, a bit of dark humor that delighted beachgoers. Over the decades, waves and weather have split the Atlantus into three pieces. The stern section remains the most visible, a gray slab of concrete jutting from the surf. The midsection has slipped completely beneath the surface. The bow appears only at low tide, like a secret the ocean reveals and then takes back. Each year there is a little less to see, and each year tourists still come to Sunset Beach to watch the sun set behind what remains.

The twelve concrete ships of the Emergency Fleet were an experiment born of wartime desperation. Most were scrapped or scuttled within a decade. A few found second lives as breakwaters or fishing piers. The Atlantus is the most famous of the twelve precisely because of her failure. Stuck in the sand off one of America's most popular resort beaches, visible from shore, photographed on postcards since the 1940s, she became a monument to both ingenuity and miscalculation. The concrete that was meant to carry cargo across the Atlantic now slowly returns to the sea, grain by grain, while visitors stand on Sunset Beach and try to imagine a world desperate enough to build ships out of stone.