AT THE AGE OF NINE, when most kids are just catching on to the lick-the-frozen-flagpole trick, Karl Stanley decided he wanted to build a submarine. The quest began in his Ridgewood, New Jersey, elementary school, with a reading-comprehension exercise about a group of kids who built a sub to find, fittingly enough, an underwater monster. "When I read about how much of the world is underwater and how little of it we've seen," Stanley says, "I wanted to see what nobody else had."

Stanley's penchant for exploration is matched by his disdain for authority, and both of these manifested at an early age. As a teenager, he snuck out of his home to raft the nearby Saddle River, leaving a Post-it note on the phone that read, "I left to go see the world—be back tonight." At 14, feeling confined by his parents, he ran away to a family friend's house; when he refused to return home, his parents hired private detectives to drag him to a reform school in Maine. He was expelled 13 days later, after an unsuccessful escape and a shower strike. Then he was packed off to a mental hospital in New Jersey, where, after six weeks and another escape attempt, a panel of doctors proclaimed him fit to leave, though a few diagnosed him with what Stanley remembers as "defiance-of-authority syndrome." "Jacques Cousteau got kicked out of high school for breaking 17 windows," Stanley says.

He went home to Ridgewood and focused his prodigious energies on building a submarine. The 15-year-old read everything he could on the subject and canvassed the submarine community for advice. Still, he managed to find trouble. After high school graduation, Stanley was arrested for attempting to detonate remote-triggered fireworks from the roof of a police station on July 4. At 18, he went to Florida's Eckerd College to study marine biology but discovered only "boring classes with lots of math and no job prospects." The self-taught engineer, it's worth mentioning, is not fond of math. He studied history instead, a subject that appeals to his inquisitive side. "I don't think you have to have an education in anything to be an explorer," Stanley proclaims. "You just have to be curious enough to want to know. What did Christopher Columbus have a degree in?"

His senior year, Stanley towed his partially built sub to Florida, and with money he'd earned from selling used college textbooks out of his dorm room, he completed his first submarine for $20,000. The week after graduation, in 1997, off the coast of St. Petersburg, he took his Controlled by Buoyancy Underwater Glider (CBUG) on its first dive, to a depth of 15 feet. The next year, at a Florida diving trade show, he met a Roatán resort owner looking for a unique attraction; Stanley moved to Honduras and opened a submarine tourist operation where, for $185 a pop, he would take customers in CBUG to depths of 725 feet.

Tempted by the unknown, Stanley went back to the drawing board in 2002 to construct Idabel, named after the Oklahoma town where he built it. (An Idabel-based tire manufacturer named Buck Hill had met Stanley while vacationing on Roatán and offered to help him.) It took two years to build the submarine, which Stanley designed to explore Roatán's waters to a depth of 3,000 feet.

Roatán has a history of maverick seafarers. During the colonial era, the 33-mile-long, banana-shaped island of secluded bays and treacherous reefs offered the ideal pirate haven. Stanley calls Roatán's location, which sits on a buckle of basalt above the 25,216-foot-deep Cayman Trench, "perfect. You can stand on the shore and throw a ball into water half a mile deep."

Like the buccaneers of yore, Stanley flouts the protocol that governs much of the nautical world. "His submarine would never pass certification, not even close," says Robert Wicklund, managing partner of Florida-based Deep Sea Adventures, a company that specializes in submersible operations. In the United States, the American Bureau of Shipping typically certifies commercial seacraft (including submarines) that meet certain design and maintenance standards. "Karl is very thrifty and makes things work on a small budget," Wicklund says. "But he's too much of a risk taker for most of us in the business. The thing is working, but I wouldn't go down in it." Stanley says building the sub for certification would've doubled the cost of the $200,000 Idabel, an expense he couldn't afford.

Stanley's been working on Roatán illegally, charging tourists as much as $1,500 for a shark dive. He has collected rare seashells with his submarine, selling them for thousands of dollars apiece, and sunk a 110-foot ship at 1,400 feet to serve as a sharking base, all without permits. As his Honduran lawyer, Raúl Barrientos, puts it, "he has a lot of problems."

The renegade submariner has made some powerful enemies. He's quarreling with his Honduran neighbor, Rene Zeron, over the boat dock where Stanley keeps his submarine. Their relationship bottomed out in 2004, when Stanley, in a dispute over dock access, made injudicious use of a sledgehammer on Zeron's gate. "He's intractable," says the 64-year-old local, who rents waterfront cabanas to tourists. Though Zeron has no desire to take the law into his own hands, he says that Stanley's behavior would not sit well in the rest of Honduras, where violence is more common. "If he were on the mainland," Zeron says, chopping his arm across his chest like an ax, "he'd be dead."

Stanley claims that last year, when he inquired about extending his side of the dock, the municipality told him it wasn't issuing any more permits. Weeks later, Zeron extended his dock, where the vice mayor, Delzie Rosales, now moors her fishing yacht. A not-so-pleasant confrontation ensued between Stanley and Rosales. "Karl is running a business illegally," says Rosales, who thinks Stanley should be deported. "If I?was the mayor, it would be a different story."

As for Stanley, he says, "I needed to get all my paperwork done somehow, and this is as good a reason as any." He's quick to point out that until now, the government has condoned his presence—and that of the thousands of other working expats who support the island's $14 million tourism industry. Yet Stanley has a much higher profile than the average dive instructor and has been ordered not to work by the government. Instead he's turned to philanthropy; he's still taking clients down in Idabel but requests that they donate the fare to the Sol International Foundation, a local nonprofit that runs after-school programs. "He's very interested in the island growing educationally,"says Sol president Dave Elmore. Stanley's doing charitable work while burning his adversaries, and it's difficult to tell which he finds more gratifying.