Divers go to incredible lengths to recover a 16th century shipwreck

In June 1991, treasure hunters discovered some iron helmets, guns, jars and cannons about 15 feet underwater in the Bahamas. 

The divers, who worked on the sea floor eight to nine hours per day, breathed through a "hookah system" in which an air compressor on the boat could provide air to five divers at a time [Credit: Mel Fisher Maritime Heritage Society and Museum]

Archaeologist Corey Malcom realized within moments of seeing the area that the marine salvagers had come upon an important shipwreck from the European colonization of America.   

The team documented everything using drawings, measurements, photography and videotaping [Credit: Mel Fisher Maritime Heritage Society and Museum]

Stones that had to be removed were taken to a "ballast field" with the help of a lift bag so that they could be piled and weighed [Credit: Mel Fisher Maritime Heritage Society and Museum]

One diver drew (to scale) each artifact found within each unit while the other diver placed tags and bagged the items [Credit: Mel Fisher Maritime Heritage Society and Museum]

"You can write and erase with a regular pencil underwater — you just have to tie it down with a string so it doesn't float away" [Credit: Mel Fisher Maritime Heritage Society and Museum]

Malcolm described finding a sword as a "pretty dramatic scene if you're into 16th century shipwrecks" [Credit: Mel Fisher Maritime Heritage Society and Museum]

Malcom said that the excavation is only half of the process because once you find the objects, you have to transport them to the lab to know what you're dealing with [Credit: Mel Fisher Maritime Heritage Society and Museum]

Heavy iron artillery, being moved for the first time in over 400 years, had to be carried to the area beneath the workboat [Credit: Mel Fisher Maritime Heritage Society and Museum]

The main body of the ship was very fragile and couldn't be moved, so the team reburied each hull structure they found by pouring sand on them to preserve them in their exact spot [Credit: Mel Fisher Maritime Heritage Society and Museum]

Back at the lab, it's time to "take these centuries-old objects that have been drastically changed underwater and make them new again" [Credit: Mel Fisher Maritime Heritage Society and Museum]

The conservation process is so complicated because each material type requires its own specialized treatment; here the sword is being bathed in acid to remove stubborn encrustation [Credit: Mel Fisher Maritime Heritage Society and Museum]

The sword is given a final brushing of debris, then colorized for final treatment so that it matches with how it originally appeared; some of the wood from the sheath survived [Credit: Mel Fisher Maritime Heritage Society and Museum]

The salvage group from St. Johns Expeditions, usually looking to make a profit, willingly gave up the discovery (a rare move among treasure hunters) to allow Malcom's team to examine the wreck.   

After more than a decade of research (still ongoing), Malcom's team of divers and conservationists believe the ship is the Santa Clara, a Spanish sailing ship from around 1564. 

Thanks to Malcom and the Mel Fisher Maritime Heritage Society and Museum, we have an amazing look at the discovery and restoration of this invaluable treasure. 

Author: Michael Kelley | Source: Business Insider [June 20, 2012]