I wanted to illustrate how moving lower and re-positioning strobes can affect how an underwater macro shot turns out. When you have a willing subject (i.e., a subject that doesn't move quickly), you have the opportunity to perfect your lighting. In the image on the left (one of my first attempts), the background is lit by light from my 2 strobes. In order to knock out the background, I repositioned my strobes so they were pointing *in*, towards my camera. This goes against everything underwater photographers are taught, but if the water is clear enough and your subject close enough, it will not create enough backscatter to be a problem. With strobes pointing more or less inward, you are using the outer falloff of each strobe to light your subject. No light reaches the background reef or sand. If you shoot with a fast shutter speed, low ISO, and small-ish aperture (in this case: 1/250s, f/9, ISO 160), your background is probably going to be completely black. For dramatic effect, get lower, so the shot is taken from the same level as the subject. A 45-degree viewfinder helps to make this possible; there is no reason to create neck problems by trying to use a 180-degree viewfinder. 
