The leader of the expedition that found the RMS Titanic confessed yesterday that after months of searching the North Atlantic with millions of dollars in state-of-the-art high-tech equipment he and his colleagues actually located the hull of the legendary liner with a 25-year-old glorified fish-finder.

"It was a fluke," said Robert Ballard, director of the Woods Hole Oceanographic Institution's Deep Submergence Laboratory. "Any fishing boat could have done it."

But as Ballard told a mesmerized news conference at the National Geographic Society yesterday, in the first full story of the Titanic expedition, the keys to searching beneath the sea are "knowing which drawer to look in" and how to recognize what you find.

While he stressed the advances in undersea technology the Titanic search had produced, Ballard said it was the human artifacts that he found most affecting.

He distributed pictures of wine bottles and a silver tray, scattered across the ocean floor, the last traces of a world in which male passengers in first class handed women and children into the few lifeboats, then changed into formal dress to go down like gentlemen. More than 1,500 died.

Ballard confirmed the long-known fact that another ship, the Californian, was close enough when the Titanic struck an iceberg to have rescued everyone aboard before the "unsinkable" liner went down three hours later.

Crew members from the Californian said after the disaster they could see the Titanic's running lights but didn't realize the ship was sinking and couldn't imagine why it was firing rockets.

In fact, Ballard said, the Californian may have been as close as four miles, halted throughout the night in the ice field of which it had warned the Titanic by telegraph hours before.

The Californian's telegraph operator went off duty just before the Titanic began signaling for help.

But it was the details of the search itself that dominated the news conference -- related by a scientist who admits being "in love with technology."

For the past 10 years, when not probing such depth-shrouded geologic mysteries as the East Pacific Rise or the volcanic rifts off the Galapagos Islands, where in 1979 he discovered an entirely new process of life, the 43-year-old oceanographer immersed himself in the history and mystery of the Titanic and the still, star-studded night when the great ship went down.

He and his colleagues from the French Institute for the Research and Exploitation of the Sea (Infremer) "became scholars of high note," poring over the eyewitness accounts and dozens of books about the disaster of April 14-15, 1912.

They examined the logs of the other ships nearby that night: the Californian and the Carpathia, which heard the first SOS ever telegraphed and raced 58 miles north to pick up the Titanic survivors.

A marine geologist by both training and passion, Ballard spent years analyzing the ocean bottom in the shipwreck area 500 miles east of Newfoundland, a chill, lifeless region 2 1/2 miles down where time is measured in geologic upheavals.

It holds for Ballard an undying fascination.

He even refers to it at times as "countryside."

"The area in which we worked is an area of the lower continental rise hills," he said, "where . . . benthic storms" of current and sediment can make exploration treacherous and cameras blind.

Eventually Ballard and his Infremer colleagues mapped out a search area 15 miles square.

It was there, in July, that the Infremer vessel Le Suroit, using high-resolution French-developed sonar that surveys a kilometer-wide swath of ocean bottom, began a back-and-forth search Ballard compared to "mowing the lawn."

On the French vessel, Ballard said, he encountered "miserable" weather, "much more adverse than ours," with 40-knot gales and 13-foot seas common.

But, Ballard said, they managed to cover 80 percent of the search area before the U.S. Navy research vessel Knorr, chartered by Woods Hole, reached the scene.

The Knorr, "blessed with incredible weather," took over towing a Volkswagen-sized sled of computer-controlled television cameras and lights developed for the Navy at Woods Hole and called the ARGO system.

There is nothing really revolutionary about the structure and equipment of the ARGO itself, Ballard said.

What is new is "how it all fits together" and the software.

The Knorr spent a lot of time, Ballard said, eliminating some very difficult canyon terrain, then moved east to search an area of immense sand dunes that "looked like the Sahara desert."

By that time, he said, the expedition had been "mowing the lawn" for a long time and "the fever had cooled somewhat" among those on watch.

"Popcorn was being popped, people were listening to music and it was a very low-key, relaxed environment."

But those aboard were "sensitized to debris," Ballard said, and when a riveted metal cylinder five times the height of a man appeared in shadowy gray image on the ARGO video monitor, they knew what they had: a Titanic boiler.

The first thing Ballard did after finding the boiler was retrieve the ARGO system from the ocean floor.

"We bailed out," he said. "The sonar was showing debris all around . . . I wanted to know 'Where is this monster that's going to eat my equipment?' "

It was while starting to survey the debris with sonar that the Knorr ran over the 882-foot-long, 175-foot-high hull of the Titanic itself, receiving an echo on the ship's built-in depth-finder impossible to misinterpret.

"We knew right away where the mass of the Titanic was . . . and we began approaching it from the side to 'see' it" with the sonar.

"We ran along the side and we saw this massive wall that just blocked out our side-scan and ran around it to lock it in" to the ship's computerized positioning system.

It was only then, Ballard said, that they were willing to lower the ARGO again and risk towing it through "this nightmare of stacks and wires and cables."

The actual survey operation, Ballard said, involved towing the ARGO back and forth across the Titanic at the end of a 2 1/2-mile cable.

So absorbed was the crew in exposing the miles of television tapes and 20,000 photographs of the Titanic -- over which, Ballard said, a legal dispute with the French had been settled -- that they had relatively little time to analyze what they had.

He apologized repeatedly for what he insisted was the sort of too-hasty analysis that no scientist likes to make. Nobody present voiced a complaint. Instead, James Hass of the Titanic Historical Society rose to say, "Thank you for giving us the adventure of our lives."