John Fairfax stands beside his 22-foot-long, orange-colored Britannia at King George V Dock in London on Jan. 3, 1969. (Peter Kemp/ASSOCIATED PRESS)

John Fairfax, who died Feb. 8 at 74 near Las Vegas, once called himself a “professional adventurer.” A former big-game hunter and cigarette smuggler, he achieved international celebrity in 1969 for being the first person in recorded history to row alone across the Atlantic Ocean.

Two years later, Mr. Fairfax made a transpacific crossing in a rowboat with his girlfriend — the first such triumph by a two-person crew. He wrote books about his voyages, the culmination of a lifetime of wanderlust.

Mr. Fairfax, who was raised mostly in Argentina, said he first left home at 13 to “live like Tarzan” in the South American jungle. He accumulated exploits as others might professional accolades or club memberships. He was variously a shark fighter, ocelot hunter, mink farm operator and authority on baccarat.

He was best remembered for his accomplishments as an oarsman. The fascination with rowing began in childhood after he read a Reader’s Digest article about two Norwegian adventurers who in 1896 became the first in known history to row successfully across the Atlantic Ocean.

Bronzed, sinewy and charismatic, Mr. Fairfax persuaded the noted English boat designer Uffa Fox to build him a vessel fit to weather the Atlantic. If it capsized, the 22-foot-long, orange-colored Britannia would right itself within seconds.

For two years, Mr. Fairfax prepared in London’s Thames River. He embarked Jan. 20, 1969, from Las Palmas in the Canary Islands, bound for Miami. Currents threw him down to the West African coast before he could make his way to Florida.

One hundred eighty days later, he landed in Hollywood Beach, north of Miami, after a voyage of more than 5,300 miles. He battled sharks, exhaustion, diarrhea, backaches and blisters.

At times, he pulled alongside freighters that supplied him with fresh water and food, but the trip was marked by extreme loneliness. A Russian sailor named Svetlana, he told the New York Times, perked up his spirits with a kiss.

Loneliness was less a factor on his next voyage, planned from San Francisco to the Great Barrier Reef of Australia. He brought along his girlfriend, Sylvia Cook, a London art gallery secretary who might have seemed underqualified because of her inability to swim.

On April 26, 1971, they boarded a 30-foot, Fox-designed vessel christened Britannia II. Over the next 361 days, they were blown down to Mexico by a storm and survived a cyclone by strapping themselves in leather harnesses. There were shark attacks, and Mr. Fairfax suffered a gash in his upper right arm from a shark bite. “It was not really the shark’s fault — it was mine,” he told a reporter. “I had speared a fish, and the shark took it off my spear. So I speared him and he did not like it, so he had a go at me.”

He and Cook said they enjoyed each other’s company and would part as friends. Reporters eager for the “Adam and Eve” angle — two comely people, alone at sea for nearly a year — were disappointed. As Cook told The Washington Post after the journey, the bed was soaking wet all the time. “You try it in a crummy little boat like Britannia at sea,” she said.

“It was a miserable journey,” Mr. Fairfax said at the time. “I don’t care if I never touch another oar. I have another idea in mind, but it won’t involve any rowing.”

John Fairfax was born in Rome on May 21, 1937, to a British father who worked for the BBC and a Bulgarian mother. His parents’ relationship faltered, and he moved as a boy with his mother to Buenos Aires.

At 17, Mr. Fairfax made his way hundreds of miles into the Paraguayan jungle in a carved-out canoe and wrote a Spanish-language book about his adventures, “Vagabundos Bajo El Sol” (“Vagabonds Under the Sun”). A picture from the book, published in 1957, shows him shirtless with a large snake draped over his shoulders.

His mother, hoping he would settle down, found him work managing a mink farm. It didn’t last. He found his way to London, where he made up his mind to fulfill a childhood dream and row across the Atlantic.

Mr. Fairfax later tried unsuccessfully to salvage a load of valuable metals from a sunken vessel. He also planned a skiing trip across Antarctica, but in 1981 he postponed it indefinitely to marry.

He died at his home in Henderson, Nev., after an apparent heart attack, according to his wife, Tiffany, an astrologer who writes the Cosmic Jackpot column for a Las Vegas area publication. She is his only immediate survivor.

Kenneth Crutchlow, executive director of the London-based Ocean Rowing Society, called Mr. Fairfax a man of “determination, self-reliance and confidence.”

Crutchlow grew momentarily irritated when asked whether it seemed crazy for anyone to mount an expedition rowing solo across an ocean.

“People don’t seem to understand there are those who like to go to university, have a career and die in their beds,” he said. “And there are others who see a different path and take a risk.”

Crutchlow added that he was in Florida when the Britannia landed in 1969 and witnessed a Miami Herald reporter sharply questioning Mr. Fairfax’s ability to kill sharks. He said Mr. Fairfax rented a boat, poured fish blood in the water and killed a “decent-sized shark,” which he then dumped on the front door of the newspaper office.