The Wollangambe River passes through numerous sections of canyon on its way to the Colo River. The two most popular sections lie below Mt Wilson, and are excellent lilo trips on a summer day. The notes below describe the lower tourist section, often called Wollangambe 2. There are several side canyons in this section which are well worth investigating from the bottom.
Note that despite the grade of "Easy", getting to and from the canyon still requires a descent and ascent of over 300m on a track that is steep and rocky in places. The entry requires an exposed climb down tree roots. The canyon itself involves many long, cold swims, for which lilos and wetsuits are recommended, and there is a significant amount of climbing up, down and around house-sized boulders. Make sure you are fit and have appropriate gear before you go. There is no phone coverage.
Also, the time estimate of 6 to 8 hours is for a "moderately fit and experienced party of around 4-5 canyoners, including a couple of experienced leaders". Many groups will have inexperienced members, and will likely take longer - times of up to 10 or more hours are not uncommon.
From Cathedral Reserve at Mt Wilson, head along the fire trail that leaves to the west. After about 1.2km, this forks, and you veer right down a hill. At the top of a long hill, turn on to a track that branches to the right. There is a warning sign at the track junction. Follow this roughly north for 1.5km down to the river at MGA560916 (Wollangambe map). Avoid taking a minor right fork to Why Don't We Do It In The Road? Canyon (Serendipity Canyon) after about 400m, at a large anthill. There is an exposed scramble down tree roots just before you get to the river.
The canyon is pleasant and high walled, although never particularly narrow. Most of the canyon involves swimming or liloing, with generally short walks in between. There are only a couple of long swimming sections.
Not far from the start is a tricky 2m scramble down, or jump. Be careful if you jump, as there are only a couple of safe spots to land.
After another 200m or so, you pass Why Don't We Do It In The Road? Canyon at MGA565916. This is worth having a look up if you have time. If not, another 700m further on you pass Whungee Wheengee Canyon at MGA568919. This is well worth a visit from the bottom. It is possible to scramble quite some way up, but even the bottom 100m or so is superb.
The exit is at the big bend on the map at MGA572925. Watch for Waterfall of Moss Canyon coming in on the left. About 200m past this, and just past a big bouldery block up, you will see a beach on the right, and a gully on both sides. Head right up the gully, and up to the ridge. The track is fairly obvious up to when it turns into a fire trail at MGA572910. Once on the fire trail, follow it back to a grassy clearing. Turn right at the clearing, and then left after about 200m at a junction. Take the right branch at the next two intersections that are close together, and follow the track down the hill, through a gate and back to Cathedral Reserve.