Technical Free-diving and shooting underwater scene for AVITAR 2. Interview with Kirk Krack of Performance Free-diving. Kirk discusses the procedure, techniques, physics and physiology of technical free diving. Kirk also discusses how he used technical free to train actors for the underwater sequences in the new AVITAR Feature Film Download past Free-diving episodes with Kirk Krack here: 1.We go "in-depth" and discuss the philology, history and mindset to succeed in the sport of Free-diving 2.Intro to Free-diving with Kirk Krack