I can only tell You of ONE school, Divers Institute of Tech. In Seattle. It is just like the USN Diving School EXCEPT the Navy diving school has PT AND it tries to get rid of wanna be divers. Navy School weeds out those who cannot follow rules and Military conduct.
At DIT You will learn Diving just as if You were in Navy school, same hand-outs same tests and Navy Chiefs. Most of the Instructors there are former Navy Divers. You will dive the old, Old, MK-5 to the most Advanced Mixed Gas Hats by Kirby-Morgan.
I went by DIT last month and was told that the course is 6months in duration covering all diving Including Saturation Diving. Mixed Gas Diving is done in Lake Washington in Seattle.
The diving course is Primarily for the Oil Fields of Mexico and the North Sea. Lots of Air Divers in the Pacfic Northwest have attended DIT. Lots of the information Passed along is of Underwater Construction using Underwater Chainsaws, Drills, and Impact Wrenches. Underwater Welding and Burning is also done at DIT.
I believe that DIT has been a big help to me over the 30+yrs working underwater........Bill