I've spent a fair amount of time taking photos on my whitewater kayak trips. There really is no easy way that I've found to take pictures while inside a kayak.
I've used several different methods of protecting my cameras. First was simply placing them in a dry bag, which works, but dry bags do leak sometimes and are also a hassle to roll and unroll all the time. They don't provide much impact protection either, so a softcase for my camera was necessary and also a hassle.
Second, I tried an underwater casing, which worked well for protecting the camera and keeping it dry, however, it's bulky and awkward. However, the biggest problem I had was getting water spots on the lens. Since I whitewater kayak, I'm continuously being splashed or rolling, hence the water spots. This may be less of an issue with recreational touring. This could possibly be alleviated by applying CatCrap or some other optical water shedding agent, but I wasn't sure how that would affect the optics and since the case wasn't mine, I did not try it.
Thirdly, I use pelican cases. They offer great impact protection and are waterproof. I have heard about the gaskets failing and condensation getting inside the case, so sometimes I'll put the camera inside a ziplock inside the Peli case. The main problem I have with this method is I have to wait for my hands to dry off until I can handle the camera which usually isn't long if I have a dry towel in my case, but is still long enough that I might miss the shot. This is the method I use now and am the most happy with. It does have its drawbacks, but seems to work the best.
On a side note, I've all but given up trying to take images while in my kayak. They are simply too unstable and squirly to do so. Once again, this may be easier in a Rec kayak. Even when I had the underwater housing, I couldn't compose an image well enough while in my kayak to make it worth it. All of my successful images have been taken from the shoreline.