The superstars of underwater exploration floated up to Capitol Hill yesterday to battle over a subject as old as Noah's Ark: How and when does a shipwreck become history -- and who, in any case, does it belong to?

In one corner, wearing a cotton cord suit, silver-rimmed glasses and an entrepreneurial chip on his shoulder, was Mel Fisher, up from Key West and a week of hauling emeralds and silver from the $400 million Spanish galleon Nuestra Sen ora de Atocha, the richest shipwreck ever found.

In the other, wearing a swashbuckler's mustache and a look of pain, sat Robert Marx, jetted in from Indonesia and his search for a 1511 Portuguese galleon called the Flor do Mar, whose gold elephants, jeweled peacocks and Batavian porcelain, he says, will make the Atocha look like a cut-rate canoe.

From his Bronze Age shipwreck off Turkey came George Bass, waving the banner of scholarship and the imprimatur of the Institute of Nautical Archaeology and of the Smithsonian, where he lectured last night.

And from Woods Hole, Mass., came explorer-technologist Robert Ballard, buttonholed briefly between last month's internationally heralded discovery of the RMS Titanic and a December voyage to the Mountains of the Sea.

Marx, Ballard and Bass favored a bill that would modify in some degree the ancient laws of admiralty and marine salvage -- which add up, basically, to "finders-keepers" -- that have ruled the sea since waterborne commerce began. He wouldn't mind, Ballard said, if some of the wine bottles, silver trays and stained glass on the ocean floor around the Titanic were recovered for a museum -- "but I'd hate to see them on sale in Neiman-Marcus."

Fisher liked finders-keepers just fine.

"I think what this boils down to is the nationalization of the salvage industry," he drawled to a House Merchant Marine and Fisheries subcommittee. "It goes against every free enterprise kind of idea."

Having spent 10 years and $1.6 million on 111 federal court cases nailing down his unrestricted claim to the Atocha, the potbellied former chicken farmer was not eager to move to a new system of regulation that would effectively move underwater law from the federal courts to state agencies.

Before he moved his claim to federal courts, Fisher said, he tried working with the State of Florida, but "it was impossible.

"They put regulatory bureaucrats on our boats and said we could only work 40 hours a week," he said. "We work all the time when the weather's good, not when some bureaucrat wants to. And I had three boats, and they said I had to have an agent on each boat. But they could only afford one. So I had to meet the payroll of the other two state agents, buy their diving equipment for them, and teach 'em how to dive, and teach 'em archeology. And then they said, 'Well, you can only work them 40 hours a week.' So I had to get six of these agents, and it just got worse and worse."

Treasure hunting, he said, belongs properly to the responsible venture capitalist who gambles his money and time on the chance of a payoff in the end. "Salvagers and archeologists are a team," he said. "We do a damn good job."

But subcommittee Chairman Barbara Mikulski (D-Md.) wondered if time wasn't catching up with the free-booting days offshore. And Ballard agreed.

"To many Americans," he said, "underwater treasure hunters and salvagers are marine cowboys with the wind blowing in their face and the wild seas to ride." But "the technological genius most Americans are so proud of has entered the deep sea in full force and placed before us a new reality." The archeological treasures now accessible, he said, are "the pyramids of the deep," and man "can either plunder them like the grave robbers of Egypt or protect them for the countless generations which will follow."

Marx, a self-taught archeologist who began diving in 1949 and has published 31 books on shipwrecks and their timeless lure, has watched lawyers and corporations invade a field he long dominated with just a suntan, energy and an adventurer's guile.

All the wrecks in the world were once his agenda, he said before the hearing, with something like sadness. "I used to own 'em all."

Still, he "always held the opinion that 'finders-keepers' should never apply to shipwrecks or anything old which one might find under the sea," he said. "I knew from the start there were only a limited number of shipwrecks of historical interest . . . and that sooner or later we would run out of this irreplaceable resource.

"If commercial salvors feel the restraints of working under the careful supervision of state authorities is such a burden, they should try to work in other countries with historic wrecks . . . Most countries have even more stringent laws than that now before Congress."

The full House committee also heard testimony on a bill to start international negotiations to make the Titanic site a memorial, where research and any limited recovery operations would leave the main hull undisturbed and would proceed only under government supervision.

Oil man Jack F. Grimm of Abilene, Tex., pleaded, like Fisher, for a free hand for private enterprise. He only wants to recover some Titanic artifacts for the Smithsonian and recover his costs by making a commercial film of the enterprise, Grimm said. It was basically equipment he had developed, he said, that Ballard and his French colleagues had used to find the Titanic anyway.

But it was Ballard, clearly, who had the committee most intrigued.

"You speak with a fluency not characteristic of your profession or ours," Rep. Gerry Studds (D-Mass.) told the oceanographer. "I want to commend you for the grace you have showed in going from your hands and knees in a submarine into the spotlight of the world media. I hope for your sake you don't have to do so much longer. I presume you're going right back to the bottom of the ocean."

"Yes, sir," Ballard said.

"I assume your trip to Washington has contributed to that decision. I heard you speak of 'boring organisms' . . ."