Based on your Profile...you are OW...
so you have several classes ahead of you....
Before you get into Tech...
You might want to get your recreational Deep Diver
The following 4 would be course you'd take if you go the TDI route
Nitrox
This is the entry level certification course for recreational divers wishing to utilize enriched air nitrox (EAN) as a breathing gas. The objective of this course is to train divers in the benefits, hazards and proper procedures for using nitrox mixes from 22% to 40% oxygen content.
Advanced Nitrox
This course examines the use of EAN 21 through 100% (oxygen) for optimal mixes to a depth of 130fsw/40msw. The object of this course is to train divers in the benefits, hazards and proper procedures for utilizing EAN 21 through 100% (oxygen) for dives not requiring staged decompression. (Decompression techniques may be combined with this course at the discretion of the instructor).
Decompression Procedures
This course examines the theory, methods and procedures of planned stage decompression diving. The objective of this course is to train divers how to plan and conduct a standard staged decompression dive not exceeding a maxium depth of 150fsw/45msw unless taught in conjuction with advanced nitrox, Extended Range or Advanced Wreck Courses. The most common equipment requirments, gear set-ups, decompression techniques and decompression mixtures (including oxygen and nitrox) are presented.
Extended Range
This course provides the training and experience required to competently utilize air for dives up to 180 fsw/55msw that require staged decompression, utilizing nitrox mixtures and oxygen during decompression.
Paul in VT
hope you've got lots of bucks