The Untold Story of SDI/TDI: Did We Back the Wrong Horse?

The Untold Story of SDI/TDI: Did We Back the Wrong Horse? In this episode, we dive deep into the origin story of SDI/TDI—two training agencies that didn’t just challenge the status quo, they rewrote the rulebook. From nitrox rebels to global disruptors, this is the untold saga of how a handful of mavericks took on the dive establishment and built something that might just be better than what most of us signed up for. If you’ve ever asked yourself, “Why do we teach it this way?” or “Is there a better path for my students?”—this video is for you. We start in 1985 with IAND, the first agency to teach enriched air nitrox to sport divers, back when the mainstream called it “voodoo gas.” From there, we follow the split that led to the birth of Technical Diving International (TDI) in 1994, and the strategic pivot to Scuba Diving International (SDI) in 1998—a rec agency built backwards from tech, not bolted onto it. Along the way, we explore the personalities behind the movement—Bret Gilliam, Mitch Skaggs, David Sipperly—and the innovations that made SDI/TDI a serious contender: adaptive teaching, mandatory dive computers, solo diver training, and a seamless rec-to-tech pipeline that left other agencies scrambling to catch up. And yes, we ask the uncomfortable question: Did we back the wrong horse? As a seasoned PADI/SSI instructor who’s certified hundreds over the years, I thought I had it all figured out. But tracing SDI/TDI’s roots made me pause. Their flexibility, their tech-first philosophy, and their open-door approach to instructor crossovers—it’s hard not to wonder if we’ve been riding the safe pony while the thoroughbred was out there winning races. This video is part of our ongoing dive agency history series, following the success of our PADI and SSI origin stories. It’s been the most requested topic by far, and I’ve tried to do it justice—with a bit of British humour, a few raised eyebrows, and the usual dose of dry candour. If you enjoy thoughtful dive industry commentary, cheeky storytelling, and a bit of strategic reflection, you’ll feel right at home here. 👉 FOLLOW US ON SOCIALS: Facebook - https://www.facebook.com/TheDiveHub/ Instagram - https://www.instagram.com/thedivehubphilippines/ Website - https://thedivehub.com Drop a comment below: * Have you crossed over to SDI/TDI? * Are you tempted? * Or are you still loyal to your cert card? Let’s talk shop. Let’s talk future. Let’s talk diving. #SDI #Training #DiveTraining