When the stratospherically wealthy decide to undertake a newsworthy adventure to broadcast a message, the results are sometimes disastrous. In November 1984, the dashing Baron Arnaud de Rosnay—a Parisian aristocrat and heir to a Mauritian sugar fortune—planned to windsurf from China to Taiwan across the South China Sea's 100-mile Taiwan Strait. He believed this symbolic bridging of the two countries would somehow help reconcile them. The 38-year-old had already completed six other major open-water crossings by sailboard, some of them far riskier. He'd sailed from Miami, Florida, to Cuba. He'd blasted across freezing whitecaps in the Bering Strait to reach Siberia—without permission from the Soviets. He'd slipped out of ports under the cover of night to avoid military ships with orders to stop him in the South Pacific.

On Saturday, November 24, de Rosnay set sail from Quanzhou, China—an area off-limits to tourists—with two cans of orange juice, expecting to dodge Chinese warships and make land in no more than eight hours. He promised to call home as soon as he finished the crossing. He was never heard from again.

The baron had been in trouble at sea before. In 1980, he'd set out to windsurf 500 miles

De Rosnay promised to call home as soon as he made the taiwan coast, but he was never heard from again.

from the Marquesas Islands to Tahiti, a journey he expected to take five days. On day ten he was still at sea. On day 13, having endured five aggressive sharks, blistered hands, and sun-seared retinas, de Rosnay finally reached the nearby Ahe atoll, in French Polynesia's Tuamotu Archipelago, exhausted but otherwise healthy.

So when he didn't show up in Taiwan, his wife, California-born champion windsurfer Jenna de Rosnay, wasn't overly worried. "It was rather normal not to have news from him for 24 hours or 48 hours," she recounted in an interview with a French TV station a few years later. "But by Monday night I began to really worry, and I realized it was serious."

For 11 days, Chinese and American pilots searched from the air while ships patrolled the sea. The Taiwanese combed fishing villages, thinking maybe he'd made landfall after all. But no one found a board, a sail, or a body. Satellite images later showed no storms had been in the area when de Rosnay disappeared. The wind was strong, gusting up to 37 miles per hour, but those conditions were within the baron's capabilities. "Of course, we can't discard the hypothesis that he fell from his board and couldn't catch it again," his older brother, scientist and writer Joël de Rosnay, told a French TV network. Other theories had de Rosnay somehow sailing woefully off course and drifting too far south, into pirate-infested seas, but years went by with no news of his capture or demands for a ransom. "We thought maybe he had landed on another island, that a fisherman had taken him to the Philippines, that he had amnesia," Jenna said. "You tend to hold on to any reason for hope like a life buoy."

But there was no hope. The baron had disappeared, leaving no will—and his wife and nine-month-old daughter with no husband and father. Now, when Jenna looks back at the last photos taken of her husband, she sees a tired, even worried, adventurer. The last shot shows de Rosnay swallowed by the horizon, his red sail angling over a purple sea.