Sometimes you see a rapid and think "I can do that but I don't want to". It's not always about the difficulty but more about the consequences. My buddy Matt and I went up to paddle the Silver Fork (South Fork American tributary) the other day. At the put in the very first thing was an incredibly ugly rock sieve - huge boulders blocking the river with water flowing under and through them with no possible way to fit anything the size of a kayak (or person) through. The walls of the little gorge were also undercut. We could easily put in below that but we decided to hike down a little ways and try to get the character of the river. It turns out it was more of the same - lots of sieves and undercuts, lots of boulder jumble rapids with rocks sticking up in bad places.
So we decided to walk. Not just that first rapid but the whole river. We had already set shuttle and the stretch was only four miles long so we decided we would leave the boats on the car and just hike it. There was a trail at first but it wasn't long before we were bushwacking along the river, trying to stay at river level as much as possible so we could see what was going on in there. It took a few hours but it was a great hike - an absolutely beautiful river through crumbly granite rock. But filled the whole way with undercuts and messy drops. You could definitely kayak it (it's been done many times) but I didn't really see why I would want to. We got to enjoy the beauty of the river and never felt like our lives were in extreme danger. Sometimes it's better to just walk it.