Treasure-hunter Bob Evans has spent half his life dreaming about the SS Central America, a pre-Civil War steamship decaying in the lightless depths off South Carolina. Now he's returning to the shipwreck after 23 years.

Evans, 60, set out this week with deep-ocean explorer Odyssey Marine Exploration Inc. (OMEX) to revisit the remains of the 19th-century sidewheel steamer, which sank in 1857 with the loss of 425 lives and an undetermined amount of gold. Despite recovery efforts in 1989 through 1991 that netted more than two tons of the precious metal, Odyssey says there may still be $86 million of gold lying more than a mile below the surface of the Atlantic.

"This is the greatest lost treasure in United States history," Evans, who was chief scientist on the earlier expeditions, said in a phone interview before the ship sailed.

Even with the plunge in gold last year, the metal is still more than triple its price in the early 1990s, when previous recovery efforts were suspended because of legal battles over rights to the treasure. And the rare coins that have been found at the site are selling for much more than their weight in gold.

For Odyssey, the Central America shipwreck offers another chance to show the potential gains from deep-sea salvaging.

"Our research department and the court-appointed experts all believe there is enough gold remaining at the SS Central America to warrant the expense of conducting an expedition," Odyssey President Mark Gordon said last month in an e-mail.

"It's essentially a four-story collapsed building at the bottom of the sea," said Evans, who was one of a handful of people in the ship's control room who watched the deep-water discoveries via video transmissions from a camera aboard a remotely operated robot called Nemo.

Using the robot, which can withstand deep-sea pressures of 4,000 pounds per square inch, the expeditions found gold flakes, coins and bars over the following three years, according to Thompson's 1998 book "America's Lost Treasure."

Thompson's operations were cut short by legal battles, beginning with lawsuits filed by insurance companies, banks and underwriters. Thompson's group eventually successfully defended the right to 92.5 percent of the artifacts it recovered and the right as salvor to recover what remained at the wreck.

To read the complete article, see:Sunken Gold Untouched for 157 Years Off U.S. Lures Hunter(www.bloomberg.com/news/2014-04-25/sunken-gold-untouched-for-157-years-off-u-s-lures-hunter.html)