Firefly Canyon is a good canyon on the north side of the Wolgan Valley not far from Newnes. It has a number of short abseils and swims.
The first known visit was by Tom Williams and Dave Noble in 1979. They found spikes and ladders leading up into the creek from the bottom and so may not have been the first.
See here for information on how to get to Newnes.
From the main campground, walk back 300m towards the hotel, and cross the Wolgan River at the ford. Turn left and follow the road to the locked gate, and from there through the refinery ruins to an abandoned mine shaft just across the creek at MGA447259 (AMG446257, Mount Morgan). Head up the gully keeping toward the cliff line on your left. Scramble up a log up the waterfall at the top of the first cliff line. Head up to the next cliffline and traverse around to the right of the main gully at the top. About 50m past the waterfall, scramble up some boulders against the cliff and from the top, chimney up to the next level through a narrow cleft. A step across a narrow chasm allows you to reach the top of the cliff line, and from there you can head up to the top of the ridge. Descend into the tributary on the other side. A few drops need to be negotiated to reach the main creek at MGA451247 (AMG450245). Good route finding may obviate the need to use rope.
It is about 1.5km of creek walking before the canyon starts at about MGA461256 (AMG460254). There is a 5m climb down logs, or abseil, followed by a 7m abseil down a waterfall into a pool, with a short wade or swim. Watch the rope doesn't get caught in the left hand crack. A couple more slides and a log slide follow before another abseil. This is 7m from a tree on the left, and a dry finish, or 5m from a chockstone on the left into water. Then there is a 10m abseil with the anchor around a chockstone a further 5m back across a pool that needs a short swim. Looking Glass Canyon then enters on the right. Below here, the canyon starts to open out and there is a 4m abseil into a pool, or traverse up and left for a 10m abseil from a tree to avoid the pool. Finally there is an 8m abseil from a tree on the right.
There is one more cliff line to pass. Either traverse left and walk down the ridge to the left of the gully, or do an 18m abseil beside a waterfall before heading down the creek. Once at the road at the bottom, follow it back to the ford where you started.