If you’re thinking about taking a SCUBA class, you’ll have to know a little bit about the science behind it before you can do it safely. As a former diving instructor and commercial diver, I can tell you that, yes, there are some hazards involved in diving, but if you take a course, you understand the physics behind the journey from above the surface to below it, and you practice the techniques, you’ll have the time of your life. In this first of a two-part series, we talk about sport diving; in part two, we talk about the commercial side of diving.