Skirmishes -- Kristine Kathryn Rusch

This is the fourth (I think) book in the series that began with Diving into the Wreck.  Boss and her divers are still salvaging ships, this time in the Boneyard (sort of a Sargasso of space, with my apologies to H. Beam Piper).  They're still after the mysterious anacapa drives which powered ships in the distant past and which the current technology lacks.  The knowledge has been lost and forgotten.  Nobody knows exactly how the drives work or even what they do, which makes them very dangers, but also very much desired by both the Nine Planets Alliance and the Enterran Empire.  

Also on hand are Captain Jonathan Cooper and his ship the Ivorie.  Cooper and his crew have been catapulted 5000 years into the future (Boss' era), and they still have hopes of somehow finding their way back home.  Cooper and the crew also provide the space battles, of which there are several.

So there's wreck diving, space battling, and even a bit of romance here.  Throw in plenty of suspense and several plot twists, and you have adventure SF in the old tradition.  At the end of the novel there are still some things that haven't been resolved, so we can look forward to more stories set in Rusch's Diving Universe.