This improbable yarn would have been lost forever had it not been for the astonishing discovery in April 2008 of a shipwreck in the beach sands of the Sperrgebiet—the fabulously rich and famously off -limits De Beers diamond-mining lease near the mouth of the Orange River on Namibia's southern coast. A company geologist working in mining area U-60 came across what at first he took to be a perfectly round half sphere of rock. Curious, he picked it up and immediately realized it was a copper ingot. A strange trident-shaped mark on its weathered surface turned out to be the hallmark of Anton Fugger, one of Renaissance Europe's wealthiest financiers. The ingot was the type traded for spices in the Indies in the first half of the 16th century.

Archaeologists would later find a staggering 22 tons of these ingots beneath the sand, as well as cannon and swords, ivory and astrolabes, muskets and chain mail—thousands of artifacts in all. And gold, of course, fistfuls of gold: more than 2,000 beautiful, heavy coins—mainly Spanish excelentes bearing the likenesses of Ferdinand and Isabella, but also a smattering of Venetian, Moorish, French, and other coinage, as well as exquisite portugueses with the coat of arms of King João III.

It is by far the oldest shipwreck ever found on the coast of sub-Saharan Africa, and the richest. Its dollar value is anyone's guess, but none of its treasures have fired the imaginations of the world's archaeologists as much as the wreck itself: a Portuguese East Indiaman from the 1530s, the heart of the age of discovery, with its cargo of treasure and trade goods intact, having lain untouched and unsuspected in these sands for nearly 500 years.

"This is a priceless opportunity," says Francisco Alves, the doyen of Portuguese maritime archaeologists and the head of nautical archaeology under the Ministry of Culture. "We know so little about these great old ships. This is only the second one ever excavated by archaeologists. All the others were plundered by treasure hunters."

Treasure hunters are never going to be a problem here, not in the middle of one of the world's most jealously guarded diamond mines, on a coast whose very name—Sperrgebiet—means "forbidden zone" in German. Far from plundering, officials at De Beers and in the Namibian government, who work the lease as a joint venture called Namdeb, suspended their operations around the wreck site, called in a team of archaeologists, and for a few gloriously diverting weeks mined history instead of diamonds.

It will take scholars years to study the wealth of material gleaned from the Diamond Shipwreck, as it has come to be called. "So much is unknown," says Filipe Vieira de Castro, the Portuguese-born coordinator of the nautical archaeology program at Texas A&M University. Castro has spent more than ten years studying Portuguese trading vessels, or naus, lately developing computer models based on the slender archaeological pickings available. "This wreck will give us new insights into everything from hull design, rigging, and how these ships evolved, to little day-to-day things such as how they cooked meals on board and what people brought with them on these great journeys."