International Training is comprised of three separate organizations; SDI, TDI and ERDI SDI was created in 1999 and grew out o ... f the success of our sister company TDI, which specializes in the more advanced disciplines of dive training. SDI is the only agency to require students to be taught with modern dive computers from the onset of training. TDI is the largest technical certification agency in the world. As one of the first agencies to provide training in mixed gas diving and rebreathers, TDI is seen as an innovator of new diving techniques and programs which previously were not available to the general public. ERDI is the Public Safety diving (PSD) agency that trains Police, Fire and other public safety organizations in Search and Rescue techniques in just about every submerged environment known. ERDI trains departments on how to make and maintain their own PSD teams along with being the only Public Safety diving training agency that has their own insurance that endorses its own standards. read more