Whirlpool River - This run is best done in conjunction with the next section downstream: Corrals to S-bend. A one hour hike in with one class IV drop, and a bunch of class II-III rapids with many fun play holes and wave trains. A bit of a pool-drop character with many sections similar to the lower sections of the Whirlpool.
The crux rapid is Boulder Drop(IV) located near the start of the run, it is not boat scoutable but good eddies are available on the right and left sides immediately above the drop. ~1km after the put-in the river splits into 2 channels around a gravel bar forming a short grade III rapid on either side. The channels feed back together into a 50m calm section before the horizon line of Boulder Drop. Be aware that it comes up pretty quick if you aren't familiar with the river. This drop is the result of the river being forced between a couple of large boulders, there are a couple of pressure waves and a few holes, pick your preferred line as there are several obvious options for nice clean lines.
After Boulder Drop everything is grade II with 2 interspersed grade III rapids(The first runs along a river left cliff, the second is a wave train in a right bend of the river). It is all boat scoutable with lots of one-shot waves, holes, and eddie lines to play in. The end of the upper section is immediately below the second class III rapid after Boulder Drop. Look for a trail and small beach on the river left bank, or continue downstream to the take-out at the S-Bend.