Since my first introduction to the word, scuba was merely scuba for me, an acronym for precarious underwater adventure. This was before Graham Hogg, the impassive instructor and veteran of 3,000 dives, fastened the weights around my waist, checked the meter of the air tank strapped to my back, gave us another rundown of the inflating and deflating mechanism of our BCD (Buoyancy Control Device) jackets, guided us through a lesson in keeping ears adjusted underwater to stave off increasing water pressure, allowed us a couple of dips in shallow water and made, what seemed to me, a momentous announcement &ldquoSo, shall we go in then&rdquo