I'll add a few more thoughts on Ryan's camera choices (as people have been curious). I think it was interesting because I doubt anyone else has had all four of this year's new cameras 100% at their disposal on a trip yet. Hopefully the man himself will add his some thoughts too.
My take on Ryan's thoughts on them were:
5DMk3 - best for video. Despite Nikon's gains the Canon is still the nicest SLR to shoot video with. 8-16mm works very well behind mini-dome.
D800 - Ryan's choice for stills underwater over the Canon. Always used biggest 230mm dome.
D4 - stayed on the boat doing topsides. Until Ryan swapped camera with me for a bit and tried my D4 underwater and then he used the D4 preferentially over the D800 underwater. Back to back the AF performance of the D4 is noticeable better in this situation.
OM-D E-M5 - a very capable camera, but you're always going to use a SLR if you have one. Lent out a lot.
I noticed this the other way too swapping to the D800 from the D4. But money no obstacle I'd use the D800 preferentially for tropical reef photography (scenic) and the D4 for action/big animals and cold water scenics (and I'd still use the D7000 for macro/mini-dome work).
But the bottom line is all 4 are excellent cameras. And most of the differences are not significant and only noticeable to camera geeks (like us) specifically looking for them.
Alex