The vast majority of my wildlife images are taken from the canoe. So often, this allows me to drift closer than I could get when on foot, and allows me to get images with a fairly short zoom lens that would normally need a much longer one. 

I tend to use the "Sport" mode on the DSLR for these, as it ups the shutter speed and therefore shortens the depth of field, whilst centring the focus point. All this can be done manually of course, but I find this is the fastest way to quickly change the settings and grab that shot, whilst bobbing up and down in a canoe.