I have been diving for a very long time indeed. Many years ago, before the term ‘Technical Diving’ was invented, I made a friend of cave diver Rob Palmer and we went diving together. He had some ideas on how diving could be made more adventurous without making it any more hazardous. We used ideas first put forward by Dick Rutkowski of NOAA. This included mixing extra oxygen with our air and even adding helium to it when we thought it gave us an advantage. Of course at that time we had to keep what might have been considered witchcraft strictly secret. The training agencies of the day would have pilloried us. Today those mixtures are called 'Nitrox' and 'Trimix'. We often took a pair of cylinders with us (a twin-set) filled with air but side-slung an extra tank that was as much as fifty percent oxygen so that we could cut short the otherwise onerous decompression-stop times that we needed thanks to the extra depth we went to. Sometimes, toting a massive camera, I preferred to avoid the extra encumbrance of the sling tank and made do with one cylinder of air alongside one of what we know today as a Nitrox mix of, say, thirty-six percent oxygen, both on my back. Rob introduced me to a giant of the diving world, Bret Gilliam. An American, Bret had worked for years as a US Navy diver, photographing nuclear submarines at depth when the only gas available was air. He held a record for the deepest dive on air at 150-metres deep and was and to this day remains one of the most competent divers I have ever known. Rob died later in an unfortunate diving accident (not related to the subject of this story) but Bret and I are close friends to this day, even if he does insist on calling me Mick Fleetwood!Bret was a technical diving pioneer with IANTD and then broke away from it to start TDI with Rob Palmer. Together, they wrote the first books on technical diving. If I am away in a comfortable diving destination such as Bikini Atoll or Truk Lagoon and want to dive a wreck that is just a little deeper than is suitable to use nitrox32 for, I still tend to dive with air and take a second cylinder with a richer Nitrox mix so that, in conjunction with a Nitrox gas-switching computer, I can reduce the mandated decompression-stop time I might otherwise need to endure if I only used air. This is where one gentleman in particular and a few other divers come into the story. My application of a simple rig of two independent cylinders on my back, swapping regulators when I got shallow enough not to exceed the maximum operating depth of the Nitrox, upsets some people because it was never written up in a textbook. Rob Palmer might well have done that had he lived and Bret has no problem with me using it. (I hasten to add it would be foolhardy to do this with a manifolded twin-set.) In some circles it has become known as ‘the Bantin rig’ and not always with polite intentions. My critics questioned what I would do if my air regulator stopped working (an unlikely occurrence) beyond the MOD of the Nitrox in the other tank, to which I answer that I would put the Nitrox regulator in my mouth and breath off that, making my way at a safe ascent rate up to where there would be no danger of oxygen toxicity. Oxygen toxicity is subject to total exposure that is both a combination of time and percentage. I have needed to rescue divers from more than fifty-metres deep more often than I would like whilst equipped only with a single tank of nitrox32 and although I wouldn’t ever recommend it, I am here to tell the tale. My critics seem to think it is OK to take a tank of Nitrox side-slung but not conveniently on my back. I hasten to point out that I am often doing these dives alongside those equipped only with a single tank. They wonder if I might put the ‘wrong’ regulator in my mouth by mistake. Well, anyone who does that probably should not be underwater in the first place. I go in with one regulator in my mouth and the other one is for the ascent. There is no confusion. A number of my friends including my wife have dived this way when it’s a dive that is suitable for this approach. The wreck of the San Francisco Maru in Truk and the wrecks in Bikini Atoll are good examples. It’s a way of having plenty of gas for what otherwise might be a deeper than usual dive and at the same time cutting long waits on the decompression bar. That one particular gentleman decided to become my bête noire on the Internet during the time I wrote regularly for Diver Magazine. It is ironic that he actually worked for Ocean Leisure in those days. Although I’m very happy to take four or more tanks with me if the dive requires it, as Bret Gilliam says, “If it works for you, that’s what matters.” Choose an appropriate solution and dive safely within your abilities..