This is the strainer (the green stuff on the left, not the bare stuff on the right) that flipped me and took my paddle (though I did get it back, by walking upstream and jumping in and swimming down through the same route, grabbing my paddle as I went under the tree).  It's a couple of downed trees that cover most of this ~30-foot-wide side-channel.  This photo is looking at it from the downstream side, so it's kinda hard to make out; it's not *quite* so impassable as it appears here, but still, it would have been better to stay in the river's main channel, which was wide open.