THERE IS A STORY THAT engineer Graham Hawkes tells to explain why he began building strange winged submarines, and it takes place, quite naturally, in a cloud of muck on the seafloor.

In 1984, Hawkes engineered a submarine called Deep Rover I. The one-person sub was cutting-edge technology, and Hawkes, then 37, had already established himself as a prominent ocean engineer. Deep Rover I's giant, five-and-a-half-inch-thick acrylic dome provided its pilot with a galaxy of perspective—nearly 360 degrees of horizontal view—and its manipulator claws were robust enough to carry hundreds of pounds of rock yet delicate enough to cradle an egg. The sub looked like a giant fishbowl mounted in a skeleton of metal and had a maximum depth of 3,280 feet. To this day, Hawkes calls the Deep Rover series "the most advanced conventional submarines" he has ever engineered, though he lingers over the term "conventional" with unguarded disdain.

Deep Rover I was tested in Halifax, Nova Scotia, for a Canadian company called Can-Dive, and the sub made headlines in the quiet fishing port. For its public unveiling, a stage was erected on the harbor, and a band played for local dignitaries. Flashing a streak of showmanship, Hawkes rose from the harbor in Deep Rover I wearing a tuxedo.

But Hawkes, a charming Brit with a sharp avian nose befitting his last name, had already put the sub through sea trials and come away with an unsettling conclusion. His vessel, like the scientific submarines that dominate deep-sea exploration to this day, took its propulsion cues from hot-air balloons: It traveled vertically through the water column with ease—but moved along the horizontal plane with the haste of an ant crawling through Jell-O.

During one test, Hawkes had his epiph­any. After sinking 50 feet through Halifax Harbor, he met a plucky crab standing its ground. The crustacean waved its pincers aggressively. Hawkes looked at his submarine's giant manipulator claws, then back at the crab. "At that moment," he recalls, "I realized that Deep Rover was just a big crab. We were both scurrying around on the surface of the planet, and neither of us were actually able to get up and move in three dimensions."

That revelation has dominated his life for more than a quarter century and is one that, he hopes, will shake the very foundations of marine science, change the way the world manages the oceans, and help steer humanity off a dangerous and misguided course."My God," he said to himself, sitting at the bottom of the harbor and the top of his profession, "I've been doing this all wrong."

A HUGE GULF SEPARATES the act of identifying a problem and actually solving it. The verdict on Hawkes—a transformative visionary or simply a bombastic engineer?—is still pending.

Hawkes wears the obscure crown of world's most famous submariner. He co-holds the record for the deepest solo dive in the world (3,000 feet), played a submarine-driving henchman in the 1981 James Bond film For Your Eyes Only, and made an appearance in the Dan Brown novel Deception Point as a "genius sub designer" whose plans were stolen by a maniacal engineer. He's since become the guy the world's most prominent businessmen and explorers call when they want a submarine.