BILLIONS of dollars in gold bullion lie beneath the seas. Diamonds, emeralds, priceless artifacts and works of art are lost in sunken ships, and stashed on land in forgotten caverns waiting to be found. Enter the world of treasure hunting, where intrigue, mystery and money meet in the far flung, dangerous and relentless pursuit of the big score. Hunters of these fortunes emphasize that investing in treasure-seeking ventures is extraordinarily risky. But for those that can truly afford to lose $25,000 a shot, there are few investments that are more exciting. Mel Fisher of Treasure Salvors Inc., which is based in Florida, is regarded as one of the world's most successful salvagers. However years of litigation and regulatory activity have made him reluctant to talk about investing in treasure hunting. "I think that's probably illegal" Mr. Fisher said. After emphasizing that he is not soliciting funds for such projects, Mr. Fisher explained that there is only a narrow group of people who are suited for the investment: "Most of them would probably be a 'accredited investor,' that is somebody that had in excess of a million in assets - not including their house - or else has in excess of $200,000 a year in income." He added that treasure hunting, by its "very nature," is "about the wildest speculation you can get into, except the lottery." Speculative as salvaging may be, sometimes it pays off. Mr. Fisher spent years searching for the Nuestra Señora de Atocha, a treasure-packed Spanish ship that was part of a fleet caught in a hurricane in 1622, and he eventually found it. Mr. Fisher noted that the Margarita (another ship that went down with the Atocha) is still producing valuable items, "yesterday my son brought in about a half a million bucks worth of emeralds." The salvaging operations can be hazardous to the searchers and to the investors. Mr. Fisher lost one of his sons and a daughter-in-law when a boat flipped over in the middle of the night. And the son who brought up the emeralds the other day once bumped into a barracuda on the way up from a dive. For investors, the risks may be less lethal, but quite serious nonetheless. Most treasure-hunting ventures take time, and the money allocated for recovery can prove to be insufficient, setting the stage for another round of investment for the same project. Wrangles can also occur when the loot is found - like antique gold and silver coins - and the items are offered at a valuation above what the market will actually bring. According to a published report, an investor sued a treasure hunter because the items were valued above what he could get for the coins, but the treasure hunter reported the payment of the antique coins to the Internal Revenue Service at the higher value. So the investor took a double whammy: overvalued treasure, and tax liability on the inflated amount. Experienced salvagers said that there are about 30 major treasure hunters worldwide with roughly a half dozen of them based in the United States. Some of them work exclusively on shipwrecks, while others focus on searches for lost fortunes on land, buried underground, stashed in caves or stolen by soldiers at war. All kinds of legal problems can surround a treasure find, ranging from challenges to the validity of the salvagers' claim (which in the United States gives the finder certain rights), to questions of ownership and possible contests by insurance companies who may have paid out on a sunken ship a hundred years ago and now want compensation from the recovery. One expert, speaking on condition of anonymity, said that the vast sums of uncounted wealth can act like a giant magnet for money launderers who, the source said, might work out a deal with a salvager to "find" treasures that were really planted. The launderer, through investment or actual participation, would then reap the rewards of the "recovered" items, which would then appear as a legitimate source of income. In another case, the expert said, offshore companies believed to be "mafia-linked" tried to intervene in an established treasure hunter's salvage claim, which involved a substantial sum, in an effort to muscle in. All of which goes to show that while treasure hunting may sound innocent, it's a real business. And those who get into it these days, some salvagers said, do it for pure speculation. They note that with tightened rules on tax shelters, people who purchase a limited partnership aren't looking for breaks. Rather, like in gambling, they are looking to hit it big. Martin Bayerle of Maritime Analysts Group, based in Vineyard Haven, Massachusetts, said his treasure hunting company believes somewhere between $500 million and $1.6 billion in gold and other valuables is sitting about 50 miles south of Nantucket island in 240 feet of water, in the wreck of the RMS Republic. The Republic, Mr. Bayerle said, was probably carrying $3 million of gold eagle coins when it sunk. He believes that he has just short of positive proof that the treasure is there, but of course, until its actually found, no one can really know. How much could one profit if one got lucky? Roughly by a 20-to-1 ratio, if the gold is on board and recovered, Mr. Bayerle said. So a 20 to 1 on the limited partnerships, $25,000 translates to a cool half million. The partnerships, Mr. Bayerle notes, are available in Europe now, and should be offered in the United States next year after a regulation D filing is made with the Securities and Exchange Commission. Mr. Bayerle has been trying to get at this gold for a while. "In 1987 we were 40 feet from where we should have been, we were in the wine lockers" where they recovered some lovely 1898 Moët, but no gold. Maybe next time. "The type of investor we're approaching," Mr. Bayerle said, "is someone who can afford to lose $25,000."