The Nautical Chart by Arturo Perez-Reverte.
A gift from a friend who was wowed by it. So far, I am too, but I just started it. Really well written. Here's the amazon summary:
A treasure hunt for a Jesuit ship sunk by pirates off the coast of Spain is the plot on which Perez-Reverte's new novel turns, but a love story is the real heart of this nicely crafted, carefully told adventure. A suspended sailor happens on a maritime auction in Barcelona, where he meets the beautiful Tanger Soto, a museum curator whose winning bid buys her a 17th-century atlas that may reveal the final resting place of the Dei Gloria. Coy, the sailor, is totally smitten, so it's no surprise that he signs on to help Tanger track the sunken ship to its grave in waters he's sailed since childhood. Enlisting the aid of a diver friend, Coy and Tanger stay a few steps ahead of the crooked salvagers who've been trying to get the atlas, outmaneuvering the attempts on their lives and the efforts to keep them from the treasure.
Carl