Think about strobes for WA. The S2000 has a GN of about 20 and the YSD2 has a GN of 32. This sounds like a lot but in reality it is only one stop or so. NO strobes can light up a reef or a whale shark and any strobe can give you good CFWA stuff. WA photos are really about natural light and getting your composition correct.
For the s2000 with a GN of 20 (in air) or say 7 in water this means that
GN = Distance (meters) * f stop
so 7 = distance (meters) * 11 (for f/11) so we can light up something about 2 feet (0.63 meters) or so away
with the D2 and a water GN of 11 we can light up the same thing one meter away at f/11
so the D2 is only good for an additional foot of distance.
It looks like you are not getting any strobe light to the subject. With the same camera and strobes I shoot at 1/250 shutter, f:11 or f:16 and the strobes on manual (with magnets in). If you turn off your strobes I think you will get the same photos, but this can easily be checked at home on the kitchen table. With strobes off photos should be mostly just black, with strobes on they should be well lit.