Do not be overly alarmed if I state that the second of the two Canon D10s, which my wife and I own, let in some water in during one of the underwater sessions.
The reason was the camera’s USB port watertighting.
Both port hatches employ watertighting systems other than the classically dependent o-rings. It works well but you must keep both the rubber seal and the seal-seating surfaces are absolutely clean and free of any obstacles. Even a hair or a grain of sand is too much! This is the camera’s weak spot.
For experienced persons only
You can void the warranty if you try this
On the bright side, I managed to open the camera, pour out most of the water, and force-dried the rest by means of a hair dryer. I wouldn’t recommend this to any inexperienced person. I have had sufficient prior experience with flooded cameras, so the decision to intervene wasn’t so difficult.
I also had to decide whether to try and salvage the camera myself (a speedy reaction is essential), or to send the camera away and risk internal corrosion. So I removed the lens port and did my best to get rid of the water (and the warranty, hehe). I did my best to dry out the battery and memory card as thoroughly as possible.
After putting the camera back together, I dived with the camera several times down to its rated max depth of 10 meters. Then I checked it thoroughly for any sign of water inside its watertighting elements. Finding none, I reinserted the memory card and the battery.
Everything worked as good as before. It never happened again, so concluded that I had been careless enough not to check the sealing for obstacles before putting the camera under water and pressure.
You will probably never experience an incident similar to this one if you care for the camera properly.
Note: Thoroughly read the care instructions in the D10 manual. Canon recommends soaking the camera in fresh water for a couple hours after using it in the salt water, which helps protect seals and other camera parts.