For those of you suggesting getting a second smaller and lighter system have you seen this:
pretty cheap and gives you a double backup, housing and camera.
My bro-in-law flooded a nikon on a live aboard recently. Even if he would have had a spare, the electronics in the housing were toast and thus the second body would have done no good.
It depends on your system obviously.
And what if you couldn't determine the cause of the original flood, would you bring down the next body and lens?
I have an olympus epl2 in the oly plastic housing. If I flooded and had a spare body I could be back in business quickly. It only seems practical to me if you have optical strobes. Of course, I'd lose a lens, but I have 3 with me that I can use underwater. I actually could get a second body cheap now, but I'm more interested in spending that money upgrading.
If you're a pro on assignment, that's obviously a different situation and you need to be prepared.