IMHO, you should just get a soft-sided cooler to carry-on your photo rig. The cooler doesn't weight much, doesn't scream "expensive photo gear," and works well as a rinse tank in your shower between dives.
I agree about the Storm Case if you decide to go with a hard case.
I started with an Aquashot and carried it in a six-pack cooler. Then I bought my c5050 with a single strobe and bought a hard case. When I added a second strobe, I bought a bigger Strom Case, but found it to be too heavy. A 36-can soft-sided cooler is now my carry-on of choice.