If it's been underwater in the pacific for 5-10 years wouldn't it have lots of coral and marine life starting to grow on it?
Years ago I was watching one of Jacques Cousteau's documentaries and he was exploring the underwater wreck of the B17 BlackJack. The film of it was excellent and it was amazingly atmospheric to see the aircraft in such an alien environment. Obviously this aircraft has been underwater a lot longer but it's amazing how fast nature takes a hold.
Blackjack on Flickr - Photo Sharing!
One thing that would be really neat to do - If you got some clear acrylic and made a glass case from it, you could give it a blue tint and then use some water clear resin on top for a rippled wave effect - then it'd look like it was underwater, giving everything that slightly blue tinted colouring.