Marshmallowpie, The first thing you need is, obviously, to get dive sertified. The secound thing you need to do is forget everything that you have ever learned about photography, with the exception of composition. Water is 700 times dencer than air (If my memory serves), so light travals and affects the expoture in much diferant ways. There is also alot more microscopic things in the water that will cloud up your sceen if you don't know how to shoot underwater. Acording to Cathy Chirch, (She is on of the Gods of underwater Photography) Above water photography knolage becomes a bad habit when your under the serface. I agree with her on this 100%. Alpha: well I have three systems, Kind of, (I'm trying to get rid of one.) I have a "Nikon f100", and a "Fugi Fine Pix S1 Pro Digital SLR" that I use depending on the job. they boath use the same housing, which is a "Sea&Sea NX 100 Pro" housing that was modified by a custom housing maker in CA, to fit the Fuji camara. That housing uses 2 "Sea&Sea substrobe 120" Under water Strobes with ultra light boyancy compensation arms, and a "Nikon 17-35 MM Wide angel zoom lense", and dome port with extender. I also use the "Nikon 60 mm macro" lense for macro work, with the flat port lense housing. that's why I say kinda 3 systems, two chamaras work with 1 housing, Gates did a nice conversion, but it killed the warenty... The third chamara system is a Nikon Collpix 990 with Ikelite housing and a sub strobe 200. I used it once, and found it to be a really nice camara system, but I'm too used to the SLR's to really get cumfortable with it, and I already have too much invested in the other system to really deck it out the way I want to. (secondary srobe, boyancy arms, EXC.) Digital camaras though are definatly the way to go under water. Since you cant change film until you serface, it really gives you a new kind of freedom. the image capacity of the coolpix was what made me decide to convert my sea&sea housing to fit the Fuji digital camara. -Gabe-