THE DISCOVERY OF THE TITANIC By Robert D. Ballard with Rick Archbold Warner/Madison. 230 pp. $29.95

A solid feeling of finality comes with the last page of this book, which is written by the man who now knows more about the doomed leviathan than any other. RMS Titanic, the most written-about shipwreck since Odysseus lost his galley in the Mediterranean, is anatomized at last. If more can be known, it will only be after fresh technological breakthroughs on the world's last major frontier, that domain deliciously called the "abyssal plain."

With remarkable color pictures from the ocean floor, Robert Ballard, a self-assured technocrat ("techie" in the collegiate world of oceanographers), shows the reader the wreck as she lies; ghostly, appalling, but somehow worthy of all the fuss.

Others had speculated about the Titanic and searched fruitlessly for her for decades. Ballard found her in 1985 by assembling and using their work, by intelligent calculation and intuition of his own, and with the help of remarkable new underwater tools that permit close and speedy examination of a search area on the sea bottom. So good is this equipment that it takes no seer to realize that soon the ocean floor will be mapped and observed as fully as the land has been; and that nothing larger than a bungalow will escape the view of man.

Finding this legendary ship might once have been thought a useless and expensive exercise, but that contrarian notion can't stand examination. Techniques perfected during the search will doubtless benefit mankind enormously. Who can doubt that seabed treasures, both natural and left by man, will now be located, recovered and used, wherever they are? The U.S. Navy, which financed the successful expeditions, obviously thought it worthwhile.

Ballard has been all over the wreck. In his submersible, he has cruised past and around the ship where it lies, two miles and more down, broken in half and scattered, bow and stern 10 football fields apart. He has "walked" down the grand staircase with the help of remote cameras and plunged deep into the bowels of the great ship, where the ghosts of the more than 1,500 lost passengers still seem to live.

For the first time with a clear and factual framework, Ballard has brought the ship to life. The visual display is magnificent, aided by the superb reproduction achieved by a West German printing firm. Paintings by illustrator Ken Marschall, drawn from the thousands of photos taken by Ballard's team in 1986, help create an accurate picture of what only fish have seen for the past 75 years.

Ballard's story (told with the help of Canadian journalist Rick Archbold) is a grand American adventure, full of our native genius for improvisation, risk-taking and sentimentality. In the refreshing and thrusting egotism of Ballard we see a character of some charm: He is one of those most curious, most relentless boys-who-never-grow-up who can be found in the science labs, computer shops and chemical works of a nation still unsurpassed for technological adventuring. He plays classical music on the way down to the seabed, rock 'n' roll on the way back up. He eats popcorn, wears the trucker's billed cap, sleeps on the navigation room floor during the last hours of underwater picture-taking. Instead of a captain's stiff rig he wears a jump suit over his tees.

His book is mostly about the finding of the ship, a personal search that goes back to 1977 and provided him his moment in history. It was Sept. 1, 1985, during the "graveyard shift" after midnight, and crew members of the research vessel Knorr were wondering how to keep themselves awake at their video monitors. A techie, Stu Harris, saw something unmistakably man-made in the endless desert of gray mud through which the Knorr's underwater cameras roamed. The first thought of those on watch was to avoid becoming another ship's joke: False alarms had happened before. No one wanted to be the person to rouse Ballard -- so the cook was finally enlisted. And while he walked aft to Ballard's cabin, one of the Titanic's boilers, as unmistakable as a spacecraft on the surface of the moon, swam into focus on the video screens.

But what is most endearing about this story, which is really one of scientific sleuthing, is that it combines spirit and action, science and sweat, mind and muscle. The scientists do not take over, relegating the deckhands to a mere mention. The difficult conditions, the ship and the sea, ensure that.

Ballard's theory about what actually sank the Titanic is still only that. The most damaged area is hidden by the ocean-bottom silt into which the ship's heavy bow section plowed like a blade into suet. Ballard concludes that the scraping collision with the infamous iceberg popped a series of rivets between the iron plates that formed the skin of these prewelding ships. A long seam only three-quarters of an inch wide allowed the water to pour in so that the "watertight" bulkheads were soon overtopped. The other, deeper mystery -- why Capt. Edward J. Smith, 62 years old and given the Titanic maiden run as a crowning honor before retirement, rammed ahead at high speed into a known ice field -- may never be known.

But Ballard has given us roundness and an end to one of the world's unforgettable soap operas. We know now where the bones of the famous and wealthy victims, as well as those of the steerage passengers, are laid. We can now see the tomb of that glittering world before the Great War. It is a fine place, as Ballard writes in one of his best passages -- "a quiet place, a peaceful place, fitting for a memorial to all the things that sank when the Titanic went down. The wreck we found and photographed can stand as a monument to a mistake of arrogance, to a lost age, and to a kind of innocence we can't recover ..."

The reviewer is the coauthor of "Conversations With the Enemy: The Story of Robert Garwood," and a lifelong student of things nautical.