My advice (22 years of UW photography / video with no floods (touch wood)) is to be very careful with those o-rings. Never take them out to clean / lube unless you are in an ideal location (clean, dry, well-lit, plenty of work-space, preferably air-conditioned cool, dry air). Never open the housing in any other place. With today's batteries and a 60 minute DV tape, you should be able to get through a whole day's diving without opening the housing.
Give the housing a good soaking (1 hour) in fresh water before opening it.
Before opening the housing, dry it, using an old towel (one that is not dropping lint anymore). Clean the workbench with a damp old towel to remove dust, hair, etc. Clean your hands. Keep your finger tips clean throughout the process. Once fingers get sticky with o-ring grease, they can pick up hair, lint etc and transfer it to the o-ring so keep that old lint-free towel on your lap for regular wiping of the fingers. Inspect your fingers before you touch a cleaned o-ring.
When you do open the housing, be anal about o-ring and surface cleanliness. In a clear light, inspect everything, especially in the critical few seconds before you start closing things. Even if an o-ring was just cleaned and has been lying on the clean surface for just a few seconds, inspect it again before closing that door.
I clean the flat sealing surfaces with very large lint-free tissues. Kleenex make a good one. For the o-ring grooves, I use baby-sized cotton buds (q-tips). Find a brand that are well-spun. I only use one once and throw it, long before it starts to fall apart. Then I use a large blower pump with a narrow nozzle to blow any debris or lint out of the groove. And then I inspect, looking from all angles, particularly up against a strong back-light to help spot anything lying in the grooves.
For o-rings around ports / lenses that are rarely opened, as long as the housing had a good long fresh-water soaking, don't mess with them too often. Once every 5 to 10 dive days should be enough.
For any o-rings that you can not get to regularly, make sure the housing gets a good soaking in fresh water to avoid salt crystals forming as salty water dries next to the inaccessible o-rings.
Close hosing ports very slowly, watching the o-ring to make sure that it is gliding into place and not getting pinched out somewhere.
Get yourself a good o-ring remover. Maybe you can buy one but I have always made mine. I found that the tops of some ball point pens (e.g. Bic) make excellent o-ring removers. Pen-tops made out of soft plastic can be carved into a good wedge shape for slipping under the o-ring and lifting it out by sliding the pen-top sideways while twisting up and out. Make sure it has no sharp edges.
On the boat, dunk the housing in the fresh water bucket before the dive, Watch for abnormal bubbles. If you get a continuos stream from someplace you don't normally see bubbles (e.g. I always get some bubbles from the air leaking out of the light arms but it stops after a few seconds), don't take the housing underwater until you have fixed the problem.
Unfortunately all of the above make you into a slave of the housing. You'll see people like me out on live-aboard dive boat trips who schedule their whole day around when the housing needs soaking, cleaning, charging, etc...
I have often wondered if I am "going over the top" with all these cleaning routines. Maybe I could get by with a lot less care. But, at least I can say that, after years of this approach, it has worked for me.
Someone mentioned not jumping in with your camera. This is good advice that I nearly always follow. but occasionally that will not be possible (e.g. strong current, no one available to hand the camera to you). In that case, I jump in with the camera housing held above my head. I figure that it'll follow my body into the hole in the water and avoid the sudden smack of hitting hard water. Make sure the housing is tied to your wrist before you jump just in case you lose balance and let go of it.
I hope these help.
Regards
Peter
