Submarines were fairly slow travelers. This was true of even the most streamlined nuclear-powered boats, which could reach a maximum speed of fifty miles per hour or so. Such was the drag of water on the vessel’s outer skin—water resistance, in layman’s terms—that it could not go any faster without sustaining critical structural damage. The H2O molecules rubbing up against it created friction, and the friction would slow it down...and even tear it apart if it accelerated past a certain speed threshold.

The drone submarine was radically different. This was because of several innovations creating an effect known as supercavitation, a process by which pressurized gas ejected from rapidly spinning nozzles in the forward section of the vessel formed a kind of bubble, or envelope, around its entire hull, nose to tail.

Because of that bubble, the skin of a supercavitating submarine would never come in contact with the water. Thus, there was no friction. No drag. Nothing to keep it from shooting through the ocean like a submerged rocket.

The initial classified research for the technology making this possible had been conducted between 2000 and 2014 in the People’s Republic of China—specifically at the state-funded Harbin Institute of Technology’s Complex Flow and Heat Transfer Lab. The head of the development team was one Li Fengchen, a professor of fluid machinery and engineering. Subsequent work was done over the next decade both at Harbin and the Beijing Institute of Technology.

By the time Russia hacked the sub’s design specification in 2023, Chinese scientists had overcome nearly all the obstacles to its construction and operation.

In Crimea, the Russians went about building their own.

At fifty miles per hour, a conventional nuclear submarine would need over a week to travel from the Crimean Peninsula to Hawaii.

The drone, traveling at roughly a thousand miles an hour—its midrange speed, which was faster than the speed of sound in dry air—had come close within seven hours of its launch.

Its voyage from the Simferopol bunker had first led it south through the Black Sea into the narrow Bosporus between Bulgaria and Turkey into the Sea of Marmara. From there it swung sharply west into the Mediterranean, skirting past Laconia in southern Greece, then making a linear fifteen-hundred-mile traverse above Africa’s northern coast to enter the Tyrrhenian Sea between Tunisia and the boot of Italy. Off Valencia, Spain, it had curved south and west past the heaving limestone massif at Gibraltar to spit itself out into the open North Atlantic.