After a decade of following the adventures of Greg Brooks, who sold his Westbrook swimming-pool business to search for treasure-laden shipwrecks in the Caribbean, I’ve grown used to hearing that he might be on the verge of something big.

Once he’d stumbled across a large mound of coral-encrusted silver bars while on a scuba-diving vacation in Haiti in 1984, Brooks began reaping enough tantalizing rewards from the deep to convince him that the mother lode was a possibility worth pursuing for a lifetime.

While waiting out the bloody coup and its volatile aftermath in Haiti, where he has salvage rights to that “shipwreck soup” of the Caribbean, he has dredged up emeralds, silver and gold coins, lots of ornate porcelain pottery, bronze cannons and a valuable scrap metal used in the computer industry. By selling some of the salvage and recovering sunken fishing boats for insurance companies, his Portland-based Sub Sea Research operation has grown to include a crew of six, two large vessels and all the expensive, high-tech equipment necessary to compete in the treasure-hunting trade.

His database now contains the locations of some 150,000 old shipwrecks around the world. And if Brooks’ research is accurate, and a ballast pile and anchor he found match up as he hopes they will, one of the wrecks he’s been exploring near Cap Haitien is none other than the Santa Maria, the flagship of Christopher Columbus’ fabled fleet.

Brooks was on his way to that Haiti site and others a month and a half ago, in fact, when he made a discovery in deep waters off Key West that may turn out to be the kind of fabulous prize he’s been searching for.

“We’ve found the double ballast pile of an unsalvaged vessel that we believe is a very rich one,” he said Thursday from his office on Portland’s waterfront. “It doesn’t get more exciting than this.”

Brooks said he first learned about the site from a fisherman who brought up some shipwreck debris while hauling his anchor.

“So on the way to Haiti we checked it out,” Brooks said. “We put out a sidescan sonar and found the ballast piles and numerous bronze cannons close by. The wreck is in 190 feet of water, 40 miles offshore. On a preliminary dive we brought up several coins, pieces of eight, that were dated 1743. Based on our archival research, we’re pretty sure it’s a French cargo vessel hired by Spain to carry the king’s treasure in the Seven Years’ War in Europe. Our research shows that it’s one of the richest to ever sail.”

According to records, he said, the 140-foot vessel could hold a trove of gold, silver, gemstones and jewelry far more valuable than even the $450 million in gold that the renowned salvager, Mel Fisher, brought up from the wreck of the Atocha de Nuestra.

Brooks said he prefers to withhold the name of the ship until he has filed a federal claim that will keep other salvagers from moving in on the find. In preparation, the company’s divers will begin the process of documenting the site on videotape later this week.

“The size of the ship, the cannons, the dates on the coins – everything is falling into place to indicate this is the ship,” he said.

Although it was his dream of treasure and a sense of adventure that led him into the business, Brooks said he has become increasingly interested in the wealth of maritime history that is critical to his work. His goal is to one day put all the elements together in a Maine shipwreck museum that would allow others to experience the deep-sea wonders firsthand.

“The history surrounding the wrecks has become a fascinating part of it for me,” said Brooks, who plans to return to Key West in a week or so. “Sure, digging up the history of ships is a chore, but when the pieces of the puzzle come together, it makes it all worthwhile. I’d like to be able to share it.”