It was just another routine day of sponge diving in the cobalt waters off the coast of Turkey. While scouring the sea floor near an old shipwreck, common in these waters, a young Turkish diver noticed several objects that resembled ''metal biscuits with ears.''
The peculiar pieces lying in their silty tomb turned out to be copper ingots used by early Egyptians, among others, as the raw materials in making weapons and tools around 1400 BC.
They were, in fact, part of a historical treasure-trove that, scientists announced last week, has yielded the most extensive collection of Bronze Age artifacts ever found beneath the sea - a cargo of goods that went down in a shipwreck some 3,400 years ago.
The ship, the oldest ever excavated by archaeologists, is expected to open a significant new window on the past for researchers studying ancient trade, seafaring, and commerce in the eastern Mediterranean.
''I think this is the most exciting shipwreck ever found in the Mediterranean ,'' says George Bass, professor of anthropology at Texas A&M University and chief scientist on the project.
The find may also wash a few more waves of respect onto the emerging field of marine archaeology itself - which could use it. Although the sea is considered a rich repository of artifacts and history, traditional archaeologists have doubted the value of the science, despite its being a serious discipline for some time now.
''There are people in the universities who have never taken it seriously,'' says Daniel Lenihan, chief of the National Park Service's Submerged Cultural Resources Unit.
This stems partly from its being associated with the ''unsavory'' practice of marine salvage and treasure hunting. Even among more charitable scientists, the field was seen, at best, as good historical chronicling and, at worst, as mere relic collecting - certainly not scholarly study. Call it the battle of the pith-helmet archaeologists vs. the swimsuiters.
''Can a professor be taken seriously if he wears a bathing suit for three months out of the year?'' says one marine archaeologist of the stereotype in jest.
Now, however, that perception may be changing. Archaeologists are increasingly recognizing not only the value of shipwreck artifacts - the greatest collection of classical Greek bronze statues and prodigious amounts of Byzantine tools, for example - but also what they can add to their understanding of past civilizations.
Wrecks aren't just yielding bundles of artifacts but glimpses into the societies that produced these goods - their life styles, links with other parts of the world, technological and cultural development. ''I don't meet any archaeologist who doesn't take the field very seriously now,'' says Dr. Barbara Kreutz, dean of the graduate school of arts and sciences at Bryn Mawr College.
''It suddenly has gotten very respectable for the first time,'' adds Texas A&M's Dr. Bass.
One reason is an influx of solid researchers into nautical archaeology. Another is the quality of recent scientific papers on underwater excavations, many of which rival the standards of any reports on land digs. There is also the unusual snapshot that ships can give of the past.
With the exception of an occasional Pompeii, few land-based archaeological sites offer a pristine view of a society at a moment in history. One civilization is usually layered over another. Submerged wrecks, although less complete, represent undisturbed time capsules. ''The real Pompeiis are underwater,'' says Dr. Richard Gould, professor of anthropology at Brown University.
The discovery off southern Turkey, for instance, is a virtual marine museum. The cargo ship, found in waters near the coastal town of Kas, settled to the bottom during King Tut's time without capsizing. It was laden with a cargo of metal ingots, pottery, jars, gold, and ivory.
Also found with the wreck were glass ingots, the first evidence that Bronze Age people used the material, and a valuable gold goblet. Pottery showing the influence of three cultures - Greek, Cypriot, and early Phoenician or Canaanite - were also recovered.
Scientists expect the excavation, which could take five years, to yield unprecedented details about ancient shipbuilding and commerce in the region. The bones of the wreck alone, Bass writes in the January 1985 issue of National Geographic magazine, should ''push back our knowledge of Mediterranean shipbuilding by nearly a millennium.''
New tools are helping hoist history from the deep. Whereas scientists once relied on nautical charts and patience, they now tap side-scanning sonar, computerized navigational devices, magnetometers, and underwater television.
High-tech isn't a requisite on the high seas, though. Even the most expensive gear may not be able to distinguish between a pile of amphoras and a mound of rocks. Divers usually have to be sent down to check out a hunch. Bass and his Texas colleagues, in fact, have gone back to relying mainly on Turkish sponge divers to spot wrecks.
Another recent major find came about through a bit of serendipity. Last summer a diver searching for remnants of a ''Great Bridge'' built in 1777 to span part of Lake Champlain, was groping through a weedy bay when he stumbled on the ribs of three ships. They turned out to be British and French warships dating back to the mid-1700s. Now under excavation by a team of nautical archaeologists, the vessels mired in the muddy mausoleum are expected to give a rare look at colonial naval architecture.
What is fascinating history to scientists, however, is also fun for sport divers and a potential source of loot for treasure hunters. Marine archaeologists have been locked in an enduring battle with salvagers over the sunken ships. The scientists, some of whom compare the practices of today's salvors to the 19th-century robber barons who plundered archaeological digs, would like to see the same historic-preservation efforts given landlocked landmarks that are accorded to wrecks at sea. A first step in that direction - US legislation that would have given states jurisdiction over historical resources up to three miles offshore - passed the House late last session. But it didn't make it to the floor of the Senate.
A Tuesday column