I once came up from taking a picture in coz and the entire dive group was staring at me and pointing up. I look up in time to see a turtle coming right at me, right through the sun. The million dollar, to die for, turtle sunball.....I had a screwed on macro wet lens. All I could do was watch and imprint the picture on neurons that are bound to fade.
My second favorite was a photo I was taking in Hawaii. I was with an inexperienced group so the dive shop let me go down first and just asked I stay within view. I decended a sloping anchor line to a patch of sand. Thought it would be cool to lay in the sand and frame the rope the divers were gently making their way down. All with the boat in the background and clear blue water things were going well...til I felt a sharp peck between the bottom of my wetsuit and the top of my boot. I turned..nothing. Went back to framing. There it was again only slightly harder. I turned quickly to find a large 6" wrasse lurking about. So I laid down again, this time watching him...sure enough he was trying to pull off the freckles. ..OUCH!!!