I went out with my mates today on a rented boat. It was a crappy boat.
We stopped by a beach and I had my 6d + 8-15 fisheye and was taking happy snaps in the sand, etc, thinking ... weatherproof=sandproof. All okay there.
Hours later, we hop on the boat and it starts raining, mediumishy. I take my camera out of my waterproof backpack and friends say, "nooo... it's raining! Your camera will break! I say, Bah! The body and lens is weatherproof! I'll be fine".
Several hours pass, I'm still fine.
There's speckles of water on the fisheye lens pretty much everywhere, the camera has water also, everything is fine.
I would describe the amount of water on the camera .... "as if one had been hosed with water in a jovial manner while holding the camera". Something which I think, is not too much. It was definitely more water than I would expose my phone to, and certainly more than my laptop. But hey! This beast is weatherproof.
Then I take a video, and stop, and .. and .. omG! What happened to my Play button?! I press my play button and the liveview action gets invoked?... and .. AAAHH my right cursor button takes me to the menu?
In the end .... the buttons on the backplate are all confused with each other.
Now that I'm at home, I've lost the menu button, that does nothing, the AF select button will sometimes call the menu action, the right arrow calls the menu, the up arrow calls info. The left and bottom and set and info and Q still work. I haven't tested the others. I'm leaving my camera on a shelf (minus battery) for a day and then hoping it dries up and works again!
Otherwise, a visit to the friendly canon service man and hopefully they fix it under warranty. I've had it for less than a month. Maybe there was something wrong with its weather sealing when it was new.
NB: Once it got a bit sandy/rainy I didn't change the lens at all.
NB2: The fisheye works fine.
My suggestion to other 6D-ers. If your camera is wet ... press as few buttons as possible.
*goes and cancels next weekend's photoshoot.