Hi Kevin, I had a long interest in the U-166. For many years, she was the "Flying Dutchman" of the Gulf of Mexico, and I live in Texas. (Some claims were, she had been damaged just enough to sink to 60', where she achieved neutral buoyancy, and was wandering 'round the Gulf on the current, often spotted, but never photographed or gotten to by divers.) Also, I once belonged to the Civil Air Patrol, and got to hear, several times, how the CAP had "assisted" in her demise.
The U-166 was found during an undersea pipe-laying operation I believe. The last I heard, they had declared her a "War Grave" and planned to leave her unmolested. At a depth of about 5,000 feet (with the 1,200 psi pressure to go with it.) I'd image she won't be salvaged, or even photographed again anytime soon.
The whole finding of her, though, leaves me wondering just WHAT got bombed later by that Coast Guard plane. The U-166 apparently was sunk by a destroyer BEFORE that happened... (Probably some poor whale.)