I found this great mix over at SoundCloud. It's a mix from Music Library and Soundtracks of '60's & '70's. It has a cool vibe that never devolves into retro kitsch. I'm definitely going to try and track down some of this music to use in future mixes. Astromatt also has another similar mix called "Submerged - Into the Deep Blue Sea", which is excellent as well.
Between these mixes & seeing the movie "Nine", I'm on a quest to dig up old Italian & French soundtracks.
Underwater - Lost in the Sub Aquatic Cosmos by Astromatt