Instructor courses CaveDiving.com offers a variety of instructor-level courses, including SDI/TDI Crossovers, tech instructor classes, first aid/CPR and more. SDI/TDI Instructor Crossover TDI Nitrox Instructor TDI Sidemount Instructor Advanced Nitrox/Deco Procedures Instructor TDI Cavern and Cave Instructor First Aid/CPR/AED and O2 instructor