Right now there is only one real option on the market - and that is the Ikelite housing. Well priced and reasonable quality. It is a little bulky, and it has it faults, but over all a really nice housing that I have had great success with.
Seacam released a housing, but availability is debatable (expect 3 months lead time minimum for delivery, possibly more). Also we are talking huge $$$ - $3000+ for the housing alone. It is a piece of art posing as a housing. High quality, optical glass ports ($1000 for a dome port), but unreasonable for digital when you could consider the speed things upgrade. Could justify it for film when it was likely I could use the housing for a few years, but not when I expect to upgrade within a year or two.
There is at least two or three housings not too far away. Aquatica is getting closer from all reports and is defineltly making a housing and there is still rumours that maybe Subal or Nexus may still make a housing.
The Sea & Sea housing will be no better than the Ikelite, but will have a larger price tag, so unless you already have Sea & Sea ports I would probably avoid it.
So in the end it depends on your timing. If you need something now, Ikelite is the way to go IMHO. If you have time to wait, then the choices are wider. Love the camera, like the Ikelite housing. I will be investigating each new option as it becomes available to see if it is worth the upgrade.
And if you are rich you can own a Seacam (perhaps)
If you have any questions, let me know.
M