The first thing NOT to do is panic.
Yes your camera is expensive but so is a trip to the decompression chamber or worse. Remember that you are way more valuable than the camera and unlike the camera, you cannot be replaced.
If the camera is fully flooded then there is likely to be little hope that anything other than the housing is salvageable. A complete flood is reasonably rare unless you have forgotten to put the o-ring in, trapped the o-ring or have something caught in it. This is why a thorough pre-dive check on your camera is very important.
So if you notice a drip, trickle or leak you should react, as in any dive ‘situation’, calmly. Turn the camera port / lens down so that the water will collect in the lens port, running passed the camera. This will hopefully avoid some damage or at least limit it.
Now you can ascend, SLOWLY!
Should you do a safety stop? Well, remember a safety stop is just that, for extra safety. If you can remember back to that recreational dive planner, you will recall that it’s a recommendation when you come within 3 pressure groups of or at your limit or if you dive greater than 30M. Practically we do one on every dive but you can blow it off in an emergency. As a certified diver your decision is your own, I would simply continue to ascend slowly.
Once on the surface and buoyant you can hold the camera clear of the water but remember to keep it pointing port down and not slosh the water around. If the dive procedure calls for a pick up then you simply need to wait but if you are supposed to end your dive at the boat then you could be in for a surface swim. In this case do your best to keep your camera level, pointing port down and out of the water.
When you pass the camera to the boat, be clear with your instructions as to what has happened. Tell them to keep it level and pointing lens down and NOT to put it in the camera bucket!
First you want to get the memory card and the battery out. If these aren’t wet, simply keep them dry. If they are soaked then there’s no harm in rinsing with fresh water and then drying them off. This might just save your card.
If your camera is fully soaked then to be honest it’s unlikely to work again, but it’s worth a shot. Rinse it in fresh water and pack it in rice. If it’s not soaked but just got a bit of water damage and even worked then don’t rinse and again get it packed in rice.
Either way it’s a bit of a long shot. Leave it in the rice for as long as you can before you try it, and by this I’m meaning days rather than hours, the longer the better. Make sure it’s well packed and fully covered.
Then all that’s left to do it hope!
If you want to learn more about underwater photography, this course could be for you.