No, you don't NEED a $500 strobe. Frankly, you don't NEED to take pictures underwater. Many salient points have already been made. I'll add my two cents. I started with a P&S (SP-350) using the built in flash. Gaaaak! In the green Monterey water, I got underexposed pictures covered with little white blobs (major backscatter). I managed a couple of decent pics using my dive light, but generally, they were blurred, green and backscattered. Scored a great price on a cheap strobe-Oly FL-20 and housing for about $200. Wow-ttl for $200. GREATLY improved my photography, but frustrating-blown out pictures because the weak, narrow beamed strobe was too close. Underlit pics because it was too far away. As long as I took fish portraits, with rock backgrounds, from 18" I got great pictures. Everything else sucked. Added a cheapie Sunpak slave strobe for another $179. Wow! Great pictures, when the sync worked, when the optical slave worked, when the strobe wasn't flooded or didn't just quit. It's been replaced twice now. Once again it doesn't work. Finally broke down and spent the big bucks. Bought a HW ttl converter and YS-110 with a hardwired electrical cable. Now my only lighting issues are from my own inexperience in strobe placement and the limitation of one strobe. Finally, a second YS-110 that my wife just got me for my birthday. OK, I now have $1500 worth of lighting on a $500 camera/housing set-up. Did I NEED it? Absolutely. Could I have saved $500 and a year's worth of frustration by starting out with better lighting? You be the judge.