What does a new diver do when he's left in a cloud of sand and doesn't know where to find his guide? What reaction should he have when he swims over a sand dune only to come face to face with a four-foot barracuda? When I first started scuba diving, everything I saw and did was a new experience, whether underwater or above. The people I met in my diving classes all seemed to have a sense of adventure about them. My instructors...