Vast Deposits of Gold and Other Ores Lure Seabed Miners Nautilus Minerals FUTURE Geologists with Nautilus Minerals examined a drill core sample. The company plans to mine a site rich in gold and copper in the Bismarck Sea. Tom Dettweiler makes his living miles down. He helped find the Titanic. After that, his teams located a lost submarine heavy with gold. In all, he has cast light on dozens of vanished ships. Mr. Dettweiler has now turned from recovering lost treasures to prospecting for natural ones that litter the seabed: craggy deposits rich in gold and silver, copper and cobalt, lead and zinc. A new understanding of marine geology has led to the discovery of hundreds of these unexpected ore bodies, known as massive sulfides because of their sulfurous nature. These finds are fueling a gold rush as nations, companies and entrepreneurs race to stake claims to the sulfide-rich areas, which dot the volcanic springs of the frigid seabed. The prospectors - motivated by dwindling resources on land as well as record prices for gold and other metals - are busy hauling up samples and assessing deposits valued at trillions of dollars. "We've had extreme success," Mr. Dettweiler said in a recent interview about the deepwater efforts of his company, Odyssey Marine Exploration of Tampa, Fla. Skeptics once likened mining the deep to looking for riches on the moon. No more. Progress in marine geology, predictions of metal shortages in the decades ahead and improving access to the abyss are combining to make it real. Environmentalists have expressed growing alarm, saying too little research has been done on the risks of seabed mining. The industry has responded with studies, reassurance and upbeat conferences. The technological advances center on new robots, sensors and other equipment, some of it derived from the offshore oil and gas industry. Ships lower exploratory gear on long tethers and send down sharp drills that gnaw into the rocky seabed. All of this underwater machinery is making it more and more feasible to find, map and recover seabed riches. Industrial powers - including government-supported groups in China, Japan and South Korea - are hunting for sulfides in the Atlantic, Indian and Pacific Oceans. And private companies like Odyssey have made hundreds of deep assessments and claims in the volcanic zones around Pacific island nations: Fiji, Tonga, Vanuatu, New Zealand, the Solomon Islands and Papua New Guinea. The International Seabed Authority, a sleepy United Nations body located in Jamaica that presides over mineral rights on the high seas, an area its officials like to characterize as 51 percent of the earth's surface. has found itself besieged with sulfide queries. "We are entering a new stage," Nii Allotey Odunton of Ghana, secretary general of the authority, told a meeting in November. Since the Pacific islands control mineral rights in their territorial waters, they can negotiate mining deals more easily than the seabed authority, which tends to plod along by international consensus. Odyssey Marine Exploration, which recently expanded from shipwreck recovery into deep prospecting, began scouring the Pacific waters in 2010, discovering far more gold, silver and copper than expected. "There's a lot at stake," Mr. Dettweiler said. If metal prices go up, he added, "a billion-dollar deposit can turn into a hundred billion." Scientists once thought the main source of wealth in the deep sea lay in beds of potato-size rocks that could be mined for such common metals as iron and nickel. In the 1960s and "70s, entrepreneurs tried to scoop them up, but the rewards never offset the high cost of exploration, retrieval and transportation. Things began to change in 1979 with the discovery of "black smokers," sulfurous mounds and towers that gush blistering-hot water. The smokers turned out to dot the 46,000 miles of volcanic fissures that gird the global seabed like seams on a baseball. Scientists found that the smokers formed as hot water rose through the volcanic rocks, hit icy seawater and shed a variety of minerals that slowly coalesced into eerie mounds and chimneys. One, found off Washington State and nicknamed Godzilla, stood more than 15 stories high. The first wave of discovery showed that the volcanic springs harbored riots of bizarre creatures, including thickets of tube worms. The second wave showed that the mounds and chimneys - hot and cold, new and old, active and inactive - were composed of complex minerals that contained surprising amounts of copper, silver and gold.