Wasatch Steeplechase is a 16.7 mile lightly trafficked loop trail located near Salt Lake City, UT that features a river and is rated as difficult. The trail is primarily used for hiking and trail running and is accessible from June until September.
It's funny to me that they mark this as a "trail". It's actually a long connected set of trails that is the course for a trail run every year. The marked route is not accurate (maybe it once was, they used to have several different lengths/routes). I uploaded the route for the last few years. It's an amazing, grueling loop run up and over little black mountain down through smuggler's gap and back down city creek. If I wanted a 17 mile hike with some 3500' elevation I'm not sure I'd pick this one, but the run is great fun.