Yileen Canyon is one of the better canyons on the south side of Bells Line of Road. It features several sections of canyon, finishing with an abseil of up to 60m into the Grose Valley. The name comes from an aboriginal word for dream.
Ideally, leave a car at the bottom picnic area at Pierces Pass. If not, you have a 3.5km walk back up to the top car park, and then along Bells Line of Road at the end. Alternatively you can try and hitch a lift.
Drive to the Mt Wilson turnoff on Bells Line of Road, and leave the car there. There is a wide pull in area on the south side of the road just past the turnoff. Walk back east towards the top of the hill, and turn right on to a fire trail, which soon turns SSW. After 800m, the fire trail (by this stage more of a track) swings W, then S and up on to the ridge at the 1006 point. Follow the track along this ridge SW, and then S off the end of the ridge between the two branches of Yileen Gully. The track joins the east branch of the creek a short way above the junction.
There is a short canyon section just before the junction, and then there is a good section of canyon just below the junction. In the canyon is a short but awkward drop of about 2-3m, just before a 3m slide or climb down a chute (or optionally hand over hand from an anchor some distance back). There are ledges on the right and left in the pool if you want to avoid a swim.
The canyon opens out shortly after, and there is a creek walk to the start of the next canyon section. The next drop is a short way into this section, about 7m, also into a pool, usually followed by a swim. It can be jumped if you check the depth. The swim can be avoided by experienced abseilers. Immediately following this is an awkward 2m drop which can be abseiled on the same rope, or possibly jumped - but the water is shallow and the bottom is rocky. A nice canyon section follows, often with a deep wade or short swim near the end.
The creek opens out again, with some boulder scrambling, before a left hand bend leads into the final section of canyon. There is a short wade or swim, and then an abseil of about 8m from a tree on the left, with the anchor about 8m further back. The canyon opens out shortly after.
Follow the creek down through boulders to the big drop. There are usually a couple of anchor options - the tree to the right is probably an easier abseil, and a cleaner rope pull. The abseil is best done in a couple of stages, about 40m down to a huge boulder, and then 10m from a small tree, or bolts, on the right to the ground. It can also be combined into one abseil if the ropes reach.
Head left under the cliff on a track, which leads around and then down into Pierces Creek. Cross the creek and climb up the other side until you hit the Pierces Pass track - it's like a highway so you can't miss it. Turn left and follow the track back up to the car park where you left a car. If you only had one car, walk up the fire trail to Bells Line of Road, and turn left to follow it back to your car.