But soon his homesickness grew far worse than his nausea. When he remembered his mother picking pebbles out of a colander of rice, or his brother staring up at the rafters from the small straw bed they shared, it was all Ernesto could do to hold back tears. At night he dreamt of papayas with lime, fried plantains, his favorite coconut ice cream. Once, he woke up to the croaking of Cuban tree frogs and had to shake his head free of the sound. Another time, La Virgen de la Caridad del Cobre appeared to him on stormy seas.

Most of the crew was barely older than him but they had long beards and stank like Señora Portuondo’s backyard goats. Ernesto barely understood a word anyone said yet the men seemed glad for his company—clapping him on the back, shouting Gut! Gut! for any little thing he accomplished. Even the somber Captain Wruck warmed up to him after a while. When Ernesto grew downhearted, the men cheered him up with photographs of their families and girlfriends, a number of whom were named Janine and had been acquired on shore leave in France. He, in turn, boasted of Oscarito, who was a wizard at math and a regional chess champion.

A host of daily drills and maintenance tasks took up the bulk of the seamen’s waking hours. One of the radio operators, Ulf Dreher, took Ernesto under his wing and let him listen in on the hydrophone, which could capture the sounds of a ship’s propellers up to a hundred kilometers away. In return, Ernesto taught Ulf—whose face was perpetually covered with boils—useful Spanish phrases should he ever meet a pretty cubana: Me llamo Ulf. ¿Dónde está el baile? ¡Bésame, preciosa! The expressions Ernesto heard most onboard were Achtung! and Verdammt! and the seamen laughed when he spontaneously started blurting these out himself.

Ernesto grew keenly interested in the fifty-ton storage batteries that kicked into gear whenever the vessel submerged. The hammering diesel engines operated upon surfacing, or at periscope depth, and recharged the batteries in the process. An ingenious feat of engineering. They were enormous, dark and segmented, like a species of local beetle he and his brother used to collect in a cave near Baracoa. The sight of the batteries moved Ernesto deeply. He grew lightheaded, like the time he’d set foot in the Cathedral of Our Lady of the Assumption in Santiago de Cuba and the bells in its two towers began ringing in unison.

Ernesto persuaded the top mechanic, Tobias Lenz, to teach him everything there was to know about the batteries. Soon the two were communicating with grunts, hand signals, and a burgeoning vocabulary. They were delighted to learn that ‘torpedo’ was the same in German and Spanish. Although reliable, the batteries could be highly toxic—and leaked poisonous chlorine fumes when damaged. These behemoths, Ernesto realized, were both the submarines’ lifeline and a deadly threat.

Over the next months, the U-boat patrolled the Eastern Seaboard from the Caribbean to Newfoundland. To Ernesto’s surprise, the Germans regularly snuck ashore on enemy territory—Florida, the Carolinas, New York—to replenish their supplies and commit acts of sabotage. It turned out that Joachim and the men who’d kidnapped him were demolition experts. On the north fork of Long Island, they blew up a huge electrical plant and watched the entire shoreline go dark except for the flames leaping up to the heavens. Another time, they brought back a dozen stolen Virginia hams still warm from their smoking shed. Late at night, in his shirtsleeves, Joachim recounted their triumphs as the mermaid tattoo on his right bicep twitched.

The submarine got as far as the southern tip of Greenland, where it met up with a secret refueling tanker eighty miles offshore. To Ernesto, nothing was more spectacular, more mesmerizing, than those icebergs—glittering flotillas of all shapes and sizes, translucent in the pale green waters or under the twilit summer skies. How was it possible, he wondered, that this world existed on the same planet as Cuba?

In the rare quiet hours, Ernesto learned to play card games like Döppelkopf and Skat, and daydreamed of returning home. What would become of him? Would he ever see his family, or Cuba, again? How was Oscarito faring without Ernesto to protect him (though they were twins, his brother was the shyer and skinnier of the two and often got beat up by Chucho Moreno’s gang). Was life proceeding, as usual, without him? How far away Baracoa seemed from the infinite oblivion of the Atlantic!

Of course, Ernesto understood that Cuba was Germany’s enemy, having sided with the Allies and harbored Jewish refugees. But nobody onboard held this against him. When another one of the crack mechanics, Hans Fricke, got trapped in the aft torpedo tube and split his head open at the temple, Ernesto mourned with the rest of the crew. Barely twenty, Hans used to dig out stale pieces of chocolate from the bottom of his duffel bag to share with Ernesto. The mechanic was buried at sea the same moonless night he died.

The Germans had several close calls with British and American destroyers (their U-boat sank 32,000 tons of cargo while Ernesto was at sea, in intermittent frenzies of hunting fever)—not to mention a serious control room fire, and various mechanical mishaps. But nothing was so nerve rattling as when the Allies began using twin-engine patrol bombers against the submarine, often marking its position with smoke bombs and yellow dye. The fact that enemy convoys were employing their own air defense crushed the Germans’ idea of U-boat warfare—and the planes succeeded in sinking dozens of their fleet.

The seamen mocked the speech Admiral Dönitz had given them during their last furlough in Lorient, the Nazis’ U-boat headquarters in western Brittany. He’d been terse and unequivocal about their duties regarding Germany’s enemies—to pursue, to attack, to destroy. But how the hell were they supposed to fight against airplanes? Soon a cemetery of iron coffins was lining the ocean bottom. Nobody, least of all Captain Wruck, ever expected to be shouting Flugzeug! on the high seas then having to crash-dive for cover.

During one particularly harrowing battle with a British warship, the crew was trapped for twenty-two hours at a near hull-crushing depth of 280 meters. The steel shrieked, valves blew, deck plates jumped, and the boat was thrust into total darkness. Bombs and depth charges detonated above them, sending shockwave after deafening shockwave, and whipped the vessel around with violent force. The bilges flooded and every last man was ankle-deep in water, oil, and piss. Half suffocated, shivering, sick with fear, it was a matter of time before there’d be no oxygen left to breathe. The mounting pressure would crush them before the explosions did.

At the height of the siege, Ernesto whispered fifty-six Hail Marys (listening to him, the Germans learned the Spanish by heart): Dios te salve, María. Llena eres de gracia. El Señor es contigo. Bendita tú eres entre todas las mujeres. Y bendito es el fruto de tu vientre . . . In-between prayers, Ernesto focused on the pulse of his heart beating under his tongue. As they waited like condemned men in their underwater tomb, he felt closer to death than to life. Ernesto shut his eyes and bid farewell to his brother, his mother, his Tío Eufemio, everyone he loved.

The ensuing hour of fiendish silence was even more unnerving than the explosions. Had they managed to outlast death? Defy the devil? When their hope finally overcame their disbelief, the crew broke into wild cheers. It was, Ernesto told his family later, a miracle they survived. Afterwards the Germans staged a celebration complete with pork dumplings and an imaginary, seven-layer chocolate cake. It was “baked” with hazelnut flour and swathed in clouds of butter cream frosting. Joachim christened the festivities their re-birthday party.

On Ernesto’s seventeenth birthday, the Germans got him drunk on what was left of their schnapps and failed miserably to sing the Cuban national anthem, compensating with an extensive repertoire of drinking songs. Despite the extreme dangers—and a fear Ernesto wouldn’t experience again until the Cuban Revolution—he believed that his time at sea was a worthy adventure for a teenage boy, especially a sheltered one like him. Humble as his family was, how else could he have ever set foot off the island? His sole regret was that his brother couldn’t have shared in the adventure.

As the war grew worse for them—the crew spoke openly of this, grounds for treason if they’d been found out—and at the urging of Joachim, who looked out for Ernesto, they decided, at great risk to themselves, to drop him off back in Cuba instead of surrendering him as a prisoner. That, Joachim told him, would mean a certain death—and he wanted to protect Ernesto at all costs. Had they been caught, every last man would’ve been executed. By then, most of them believed they were fighting a lost war.

While on the submarine, Ernesto felt his allegiances shifting—not for the Nazis, no, but for the good men who watched over him and saved him from loneliness. Joachim even encouraged the boy to visit him in Berlin after the war. Then on a night as hazy and moonlit as that of his kidnapping, the two clasped each other like brothers on the bridge of the U-boat, off the northeast coast of Cuba. As a parting gift, Joachim gave him a precious pair of 7 x 50 Leitz binoculars.

