By Frauke Jensen
BBC News, Oranjemund, Namibia
A team of international archaeologists is working round the clock to rescue the wreck of what is thought to be a 16th Century Portuguese trading ship that lay undisturbed for hundreds of years off Namibia's Atlantic coast.
The shipwreck, uncovered in an area drained for diamond mining, has revealed a cargo of metal cannonballs, chunks of wooden hull, imprints of swords, copper ingots and elephant tusks.
Recovered treasures include copper ingots, ivory and cannons.
It was found in April when a crane driver from the diamond mining company Namdeb spotted some coins.
The project manager of the rescue excavation, Webber Ndoro, described the find as the "the most exciting archaeological discovery on the African continent in the past 100 years".
"This is perhaps the largest find in terms of artefacts from a shipwreck in this part of the world," he said.
The ship may have been unable to withstand the currents in the volatile seas off Namibia.
North of the protected mining area, Namibia's shore is known as the Skeleton Coast - associated with the skeletons of wrecked ships and past stories of sailors wandering through the barren landscape in search of food and water.
Working out whose ship this was is no easy task.
Gold coins that the Portuguese crown began producing in October 1525 mean it could not have been the vessel of the famous seafarer Bartholomew Dias, who disappeared on one of his travels around the point of Africa in the year 1500.
But there are other pointers, including swivel-guns known to have been used by Portuguese and Spanish seafarers, and the boat's shape, indicating that it was a Portuguese "nau".
There are also copper ingots carrying a clearly visible trident seal that can be traced back to the German banker and merchant family of Jakob Fugger - the main suppliers of primary materials to the Portuguese crown.
Gold and silver coins have been deposited in a bank vault.
Copper ingots carry a trident seal used by the Fugger family
Rare navigational instruments have been sent to Portugal for research, while pewter plates and jugs, pieces of ceramic, tin blocks and elephant tusks are temporarily housed in a warehouse on the premises of the mining company.
Some are being freed of their layer of sand and salt to allow for more detailed scrutiny over their make and origin.
"It represents a very interesting cargo - we have goods from Asia, we have goods from Europe, we have goods from Africa," said Mr Ndoro.
"We always think that globalisation started yesterday but in actual fact here we are with something we can date to around 1500."
The site is about 130km (80 miles) south of the Namibian harbour town Luderitz, in an area long sealed off for mining.
The mines are established by sea-walling the ocean and dredging the dry seabed for diamonds.
Portuguese gold coins are part of the recovered cargo
Pumps ensure the sea does not reclaim the land - an exercise that is costing thousands of dollars each week.
Bruno Werz, the archaeologist leading the excavations, said the shipwreck was particularly valuable because it had not been tampered with.
"This collection has not been disturbed by human interference," he said.
"We are very fortunate to have found an untouched wreck with all the material that was on site still here in one collection."
Archaeologists from South Africa, Namibia, Zimbabwe, the United States, the UK and Portugal are working on the excavation, which is due to be completed by mid-October.
Thereafter the detailed work of recording and preserving, which can take up to 30 years, can begin.
Stone and metal cannonballs and other artefacts are being covered with plastic and sand to protect them from sun and air.
Mr Ndoro said the shipwreck was a very important find for Africa.
"Here we have different African countries cooperating to make sure we have saved this ship and we have something we can show to the world."
"I am sure there will be many more wrecks to be found here," he added.
"Namibia should invest in training archaeologists."