On June 30, 1974, divers Ian Beaton and John Dimmer were being decompressed on board the Sedco 135F after making a short bounce dive to 490 feet, when, at about the 90‑foot level, Dimmer suddenly complained of shortness of breath.  He told his diving supervisor, Mike Spencer, that his chest felt like it was “full of air.”[1] Spencer followed procedure and recompressed Dimmer back down to 100 feet where his pain was completely relieved.  But when his symptoms continued to reoccur…