There's a pretty funny story associated with our search for this cache. I didn't buy the Canada topographic maps for my GPS (US$150), so I was trying to find this one with nothing much better than the GPS version of a road map (think of how well rivers are represented on road maps, and you'll get an idea of the challenge).
We'd done the Canyon City hike, and had found the Miles Canyon cache. While on the [west] side of the river, I'd convinced myself that this cache was also on the [west] side of the river. We tried several paths, some of which got pretty hairy the further we went downstream. After several false starts, we realized we must be on the wrong side of Miles Canyon. We crossed the bridge, marched down the trail, searched a bit, and there it was!
Every time I visit Miles Canyon, I think not only of the people who risked their lives trying to get their ton of supplies downriver to the Klondike region, but I also think of the fun it would be to run the Yukon River all the way to the Bering Sea. Maybe someday....