Geronimo Canyon is a good canyon tributary of the Wollangambe River. It has a relatively sustained constriction, punctuated by a number of abseils. Its name comes from the third abseil which was jumped by Glen Robinson ("Geronimo!").
Park at the fire station at Mt Wilson, and follow the main tourist track towards the Wollangambe. At about 2km a track branches left below a large (10m) sandstone outcrop, which you should follow. This contours around a gully eventually dropping in to a small steep saddle. Head left off the saddle to reach the Wollangambe at MGA543915 (Wollangambe). Cross the river, walk up to the cliff and traverse around to the left until you can easily walk up. At the top of the ridge, you should be on a track that start west and curves around to the north following the ridge. Just after a high point the track begins to fade - drop off the west side and scramble down to meet the creek at the junction at MGA539922. The canyon starts soon after.
The first abseil is a slightly awkward 7m from a tree - watch your head as the gap is narrow. Immediately this is followed by a 7m abseil from a pile of logs - needs a long sling to avoid a crack.
The next abseil is 7m using a large rock as anchor, and a long sling. This has a tricky start. Try to keep the rope out of the crack for the pulldown. The abseil can also be jumped ("Geronimo!") if you have checked the water depth. Note that the water is usually not much more than person depth, so be very careful
The last abseil is about 14m from a close tree or 12m from one further along. To get to the anchor requires a scramble along a narrow ledge to the left. Alternatively this could be done in two 7m abseils, the first from where the scramble starts.
It is a short walk from here back to the Wollangambe and then head downstream. You will soon get back to the point where you crossed the Wollangambe, and you can exit from here.