AUGUSTA, Maine — Twenty-five years ago, Maine adventurer Bill Dunlop disappeared in the South Pacific in his tiny 9-foot sailboat. He hasn’t been seen or heard from since, despite some glimmers of hope in the weeks after his disappearance.

The sad anniversary is passing quietly in his hometown of Mechanic Falls.

“It sure does not seem that my brother has been gone that long,” Donna Thompson of Chicopee, Mass., said in an e-mail.

It was August 1984 when Dunlop’s wife, Pam, and friend Ed Heath traveled to Brisbane, Australia, clinging to hopes that a small craft spotted by a Japanese ship might be Bill’s.

Dunlop, 43, had sailed from the Cook Islands, 3,000 miles east of Australia, two months earlier, promising to contact his wife along the way. No message ever came through.

Two years before his disappearance, Dunlop completed a trans-Atlantic crossing in his fiberglass Wind’s Will, setting a world’s record for a solo eastbound crossing in the smallest boat. He had left from Portland, Maine, on June 13 and landed in Falmouth, England, in late August. Sailing in the days before widespread use of GPS, he used only a $16 sextant for navigation. His boat had a radio, but no backup engine.

That death-defying journey included a gale that was so severe he had to harness himself to the boat’s 12-foot mast in order to avoid being swept overboard. Much of Dunlop’s food was ruined because seawater rusted cans and contaminated the contents.

His sometimes-harrowing 78-day journey completed, the bearded and wobbly-legged Dunlop was met by his wife and mother, and given a hero’s welcome at a local hotel.

Back in Maine, he was honored with a parade in his hometown on Sept. 25, 1982. Even the governor, Joseph Brennan, turned out to give a speech.

Hungry for a new challenge, the former truck driver set his sights on a new adventure: circumnavigating the world in Wind’s Will.

He departed from Portland, Maine, on July 31, 1983, and sailed down the Atlantic coast, through the Panama Canal and across the Pacific. Along the way, he ran aground in the Bahamas during a storm, and was mugged during a stopover in Jamaica, The Washington Post said.

In June 1984, he pulled into Aitutaki in the Cook Islands for repairs, according to a Web site set up by Thompson in memory of the brother she calls Billy.

On June 23, 1984, Dunlop’s birthday, he left the Cook Islands bound for Australia on the final Pacific Ocean leg of his 27,000-mile voyage. He is believed to have drowned in a hurricane-force storm two days after leaving the Cook Islands.

His Web site quotes Dunlop before he began his journey as saying, “I’d rather die out there trying than not do it at all.”