The treasure-laden Andrea Doria, an Italian luxury liner that sank 25 years ago this month off Nantucket Island after a collision that took 51 lives, claimed the life this week of a bank vice president from Westchester County, N.Y., who had gone diving in search of souvenirs.

The body of John Barnett, 40, was recovered Wednesday afternoon by his diving partners at a depth of 180 feet on the bridge of the massive, rusting wreck. The Andrea Doria sank in 240 feet of water about 50 miles south of Nantucket.

Barnett was one of scores of adventurers and treasure hunters who have descended into the cold, murky, shark-infested waters that surround the Andrea Doria.

They have gone in search of the $1.1 million in cash in the ship's vault and thousands of dollars worth of culpture, silverware, china and paintings scattered throughout the first-class section.

Elaborate plans have been proposed since the sinking to raise the 39,500-ton, 697-foot ship by using millions of miniature Ping-Pong balls and injections of plastic foam. Expensive salvage attempts have been foiled because almost all of the ship's treasures are on the starboard side, which is virtually inaccessible against the ocean floor.

Two additional million-dollar treasure hunts, including one by filmmaker and department store heir Peter Gimbel, are scheduled this summer.

Barnett, a marketing vice president for Citibank in New York City and a licensed diving instructor who has been diving since he was 16, was returning to the Andrea Dora for the second consecutive year when he died.

"My father took two weeks off of work to go back to the Andrea Doria. He wanted to get the ship's steering wheel [the helm] and some artifacts for his collection, to put on his wall," said Steve Barnett, 17, the victim's oldest son. Barnett was married and had four children.

Police in Montauk, N.Y., where Barnett's body was brought yesterday for an autopsy, said the victim was one of five experienced amateur scuba divers who took a 46-foot cabin cruiser to the dive site Monday.

Detective Van Quick said Barnett failed to surface with his diving partner after the first dive of what was a "pleasure" excursion, not a salvage expedition. The cause of death has not been determined, according to the Suffolk County Medical Examiner's office.

"It is incredibly dangerous for anybody to make a scuba dive for the Andrea Doria from the surface," according to Bob Hollis, a deep-sea diver from San Leandro, Calif., who eight years ago tried and failed to recover treasure from the ship.

Barnett's party used scuba equipment that gave them only enough air to spend about 20 minutes at the ship. The rest of the air was required for the descent and 45 minutes of decompression on a slow ascent.

"You have to be very experienced, in very good shape and dive in very controlled conditions in those waters," Hollis said yesterday. He said strong currents and visibility of about five feet make it extremely hazardous near the ship, which is draped with fishing nets that have snagged on the Andrea Doria from passing trawlers in the frequently fished waters.

"I think sport diving on the Andrea Doria is ridiculous," Hollis said.

Hollis and a team of divers made the first heavily financed salvage attempt in 1973 using the "saturation diving technique," which keeps divers under deep-sea pressure for the entire period of their dive. For 9 1/2 days, Hollis and two other divers moved from a pressurized shipboard compartment to a diving bell and then to waters surrounding the Andrea Doria.

Hollis' expedition was aborted when divers found themselves unable to move through debris in the mangled ship to compartments where the money and other valuables supposedly are located.

Gimbel, according to Hollis, has developed a plan to use cranes and other equipment to pull the ship apart and reach the treasure.

Gimbel said he plans to leave for the salvage site at the end of this month.

Although Gimbel refused to discuss specifics of his salvage plan, he vowed that his would be the first to salvage treasure.

"We've got it figured out," said Gimbel, who in the mid-1970s made a nationally broadcast documentary film on a failed salvage attempt at the site.

Gimbel, 53, was the first person to dive to the wreckage in 1956, 24 hours after the Italian liner collided in foggy seas with the Swedish liner Stockholm, which made port after picking up survivors.