Here's something I found online a while back.
Saving a Wet Camera
March 19, 2013
http://www.redbubble.com/people/peterh111/journal/9049428-how-to-perform-cpr-on-a-drowned-dslr1. Take the battery out as fast as you can. Yes, it doesnt take more than a nanosecond to turn the camera OFF (which is the least you should do), but even after doing so there are still volts inside going where ever the water goes. If the charge meets that moisture, your electronics will be fried. End of story.
2. Take the card out. Simple step, but in the panic immediately following the drowning its easily forgotten. I know I have.
3. Dont stand there wiping the exterior of the camera body. You are wasting valuable time. You need to get to a heat source ASAP.
4. Did you drive to your shoot? Get to the car pronto. Now take the lens off and wipe as much water as you can from inside the camera with your lens cloth or an absorbent cloth if you have one, without damaging the mirror or sensor. Tissues are NOT recommended because they will separate and strands will be left inside the body. Even shaking the body while holding it downwards will help. Turn on your cars engine, turn the cars airconditioning on full-bore and HOT, and hold the body up to the vents. Keep it there as you drive home or to your hotel, or get your passenger to do it if you have one. (Drive safe but dont dawdle.)
5. Think as you drive home. How much rice do you have? Youll need a good 4kgs, so if necessary buy some on the way home, but dont stop for a Big Mac or a pie. Get long grain, basmati, jasmine, whatever. Just get the damn rice, ok?
6. When you get home, grab a blow dryer and give the bodys interior a good going over. (The cameras, not yours.) Full blast. Give it a good 15-30 minutes or at least until you cant see any more water and your camera body is nice and warm.
7. Ideally, whilst you are doing the blow job, someone else is grabbing a pillow slip and putting all the rice in it. Now find an item of clothing. The thinner the fabric the better. The BEST item to grab is a thermal top or thermal pants or similar.
8. Insert the camera body into a sleeve (or pant). This is to prevent rice grains from getting inside the body. Dont wrap the item of clothing around the body because you want as little as possible coming between the moisture-sucking rice and the body. Now immerse the body in the rice. If the body is in a sleeve, you can leave the rest of the item of clothing hanging out, just make sure the body is immersed in rice.
9. Put the bag on a table next to a fan. This will help keep moisture from hanging around.
10. Leave the body in the bag of rice for as long as possible. Note that I havent said you can turn the camera on. That is the hardest bit resisting the temptation. Give it a week. Seriously.
11. When you finally cant wait any more and turn the camera back on, do not leave it on. Turn it back off and put it back in the bag of rice even if the camera seems to be working. CPR by rice takes time.
As I said, no guarantees any of the above will save your drowned buddy, but hopefully you can give it at least your best chance to survive. Bear in mind that repairing a drowned DSLR, if possible, can end up costing nearly as much as getting a new one, if not more.