The oldest shipwreck from Europe's Golden Age of Exploration has been found off the coast of Oman, the country's Ministry of Heritage and Culture announced on Tuesday. The wreck is believed to be that of the Esmeralda, which was part of a fleet led by legendary Portuguese explorer Vasco da Gama during his second voyage to India (1502-1503).

The wreck was initially located in 1998 and excavated between 2013 and 2015 by a partnership between the Oman Ministry of Heritage and Culture and the shipwreck recovery company Bluewater Recoveries Ltd., which is directed by David Mearns. Support for the project was provided by the National Geographic Society Expeditions Council.

Analysis of the thousands of objects recovered from the wreck is ongoing, but researchers have concluded in an interim report that the vessel belonged to da Gama's fleet — and is in all probability the Esmeralda. Their conclusion is based on extraordinary artifacts that include a Portuguese coin minted for trade with India (one of only two coins of this type known to exist) and stone cannonballs engraved with what appear to be the initials of Vincente Sodré, da Gama's maternal uncle and the commander of the Esmeralda.

If this is indeed a wreck from da Gama's 1502-1503 fleet, it will be the earliest ship from the Age of Exploration ever to be found and excavated.

View Images A ship's bell, one of the 2,800 individual artifacts found at the site, is believed to be the oldest example ever recovered. Photograph by David Mearns, Nat Geo Image Collection

The Age of Exploration

The Age of Exploration refers to a period between the mid-15th and 17th centuries when European countries sought out global maritime trade routes. Much of this activity was initially fueled by attempts to reach the spice markets of the Indian subcontinent, which at the time were controlled by the Muslim rulers of Egypt via the Red Sea.

Christopher Columbus' unsuccessful search for a western maritime route to India resulted in the "discovery" of the Americas in 1492, but it was Vasco da Gama who ultimately established the Carreira da India, or India Route, when he sailed around Africa and into the Indian Ocean, landing at Calicut (modern Kozhikode), India in 1498.

View Images A CT scan of the bell revealed the letter 'M' as well as the number '498,' leading researchers to conclude that it is a probable date of 1498, which is chronologically consistent with a ship that left Lisbon in 1502. Photograph by David Mearns, Nat Geo Image Collection

In 1502 the king of Portugal, Dom Manuel I (r. 1495-1521) reappointed da Gama as Captain-Major of the fourth Portuguese expedition to India, with a fleet of 20 ships armed with heavy guns to subdue hostile Muslim merchants. Da Gama returned from India to Lisbon in 1503, leaving behind a five-ship squadron led by his uncle Vincente Sodré to protect Portuguese factories along the southwest coast of India. Instead, Vincente Sodré in the Esmeralda, his brother Brás in the São Pedro, and the rest of the squadron sailed to the Gulf of Aden between the Arabian Peninsula and Africa, where the Sodré brothers seized and looted Arab ships.

In May of that year, the squadron was anchored at Al Hallaniyah, one of the Khuriya Muriya Islands off what is now southern Oman, when local residents warned the Portuguese that a dangerous storm was approaching. The Sodré brothers ignored the warning, and according to an eyewitness account their ships were torn from their moorings and dashed against the rocks. The São Pedro was driven ashore and most of its crew survived, while the Esmeralda and its crew perished in deeper waters.

View Images ROSEMARY WARDLEY, NG STAFF

Scholars estimate that out of more than a thousand ships that plied the Carreira da India — at the time the world's longest sea route — between 1498 and 1650, roughly 20 percent of the vessels were lost at sea. However, very few India Route shipwrecks have been found and excavated, and until the discovery in Oman the earliest-known wreck that could be conclusively identified was that of the São João, which foundered off the South African coast in 1552.

The 21st-Century Search

Mearns' team spent six months researching Portuguese archives to zero in on potential locations for the Esmeralda and the São Pedro before locating the wreck site in 1998, the 500th anniversary of da Gama's discovery of the Carreira da India. "Our team stood on top of the island and watched the waves come in, and put themselves in the place of the Portuguese, where they would have anchored and where the storm would dash them along the coastline," Mearns recalls. "Then they snorkeled around and in 20 minutes started seeing cannonballs that were obviously from a European ship."

Blue Water Recoveries returned to Al Hallaniyah island with Oman's Ministry of Heritage and Culture between 2013 and 2016 to excavate the site, which is located across a series of gullies in a bay on the northeast side of the island. High-energy wave surges — which led divers to nickname the site the "washing machine" — had forced artifacts deep into the sand.

View Images The wreck was found off of Al Hallaniyah, a remote island in the Arabian Sea. Photograph by Kristin Romey, National Geographic

Mearns credits the remote location of the sparsely populated island, some 28 miles (45 kilometers) from mainland Oman, with preserving the wreck from looters. The excavation was spurred in part by ongoing development of Al Hallaniyah.

A Ship's Bell and a "Ghost Coin"

According to the eyewitness account of another squadron captain, the ships of the Sodré brothers were subsequently salvaged and any remaining hull burned. However, archaeologists were still able to recover some 2,800 individual artifacts that enabled them to determine that the wreck site was most likely a vessel from the Portuguese squadron and possibly that of the Esmeralda.

The first stroke of luck came in 2013 when a copper-alloy ship's bell — the earliest ship's bell ever discovered — was found wedged under a large rock. A CT scan of the worn, corroded object revealed the letter 'M' as well as the number '498,' leading researchers to conclude that it is a probable date of 1498, which is chronologically consistent with a ship that left Lisbon in 1502.

While a lack of heavy guns found at the site is consistent with accounts that the vessels had been salvaged, archaeologists found breech chambers as well as dozens of stone cannonballs (35 of which feature the carved letters 'VS,' which are assumed to be the initials of Vincente Sodré) and hundreds of lead shot, which have been matched to ore from mines in Spain, Portugal, and England.

View Images One of 12 Portuguese gold cruzado coins found at the wreck site. Photograph by David Mearns, Nat Geo Image Collection

Further supporting the theory that the vessel was part of da Gama's fleet are 12 gold Portuguese cruzado coins from the reigns of Joao II (1477-1495) and Dom Manuel I, which were recovered from the wreck in mint condition, as well as a silver coin called an índio that Dom Manuel had minted in 1499 specifically for trade with India. Until the excavation, only one other example of this coin was known, leading scholars to call it the "Ghost Coin of Dom Manuel I."

The most unusual find is a copper-alloy disc featuring the Portuguese royal coat of arms as well as the personal emblem of Dom Manuel I. While the purpose of the object is still uncertain, Mearns believes it may be a part of a planispheric astrolabe. "It has some unmistakable characteristics of a navigational device," he says, "and that's always a very exciting thing to find on a shipwreck."

The artifacts are currently being conserved and studied, and will ultimately be put on display in Oman's National Museum.

View Images This copper-alloy disk features the Portuguese royal coat of arms (top) and an armillary sphere (bottom), which is the personal emblem of Dom Manuel I. While the function of the object is unknown, it may be part of a navigational device. Photograph by David Mearns, Nat Geo Image Collection

The Mysterious Fate of the Sailors

The biggest mystery encountered by the archaeologists is the apparent lack of crew remains on Al Hallaniyah Island. According to accounts, the crew of the Esmeralda (including Vincente Sodré) went down with the ship, and bodies that washed ashore were buried on the island along with survivors who succumbed later (including Vincente's brother Brás, who died of unknown causes). All in all, archaeologists estimate there could be almost a hundred members of the Portuguese squadron buried on Al Hallaniyah.

A survey of the island revealed dozens burial cairns that were determined to be non-Islamic based on their geographical orientation. However, test excavations of the shallow burials reveal a total lack of human remains. Researchers speculate that after repeated exposure to animals and the elements, the remains of the crew decayed to a point where they are simply no longer visible — a situation that has also been documented in World War Two-era burials on islands in the Pacific Ocean.