Koombanda Canyon is a short pleasant canyon flowing in to the Grose River from the north near Bell. It features a couple of short abseils and a couple of chilly swims.
Heading west on Bells Line of Road, pull off left on a fire trail just before the road crosses the railway line. This is not marked on the map, but follows the rail line. Follow this for about 1.7km and park in a clearing. Contour around the hill (the 1085 point on the map) keeping north of the major tributary, and drop in to the tributary that joins the main creek at MGA473872 (Mt Wilson). There is plenty of scrub getting into the trib. Follow the trib down to the main creek and walk down a gully just to the left of the drop (there are tapes in a tree to the right, but quite unnecessary). Head down the creek for several hundred metres to the start of the canyon.
The first abseil is only about 5m, and then there is a swim of about 20m. The second abseil is shortly after. This is about 15m from a very long sling from a tree high up on the right hand side into a deep dark cleft. You finish in waist deep water. Other anchors are possible. The final abseil is only about 3m, followed by a 15m swim. This can probably be jumped if you check for rocks.
Continue down the creek until you reach a bridge, at the old colliery. Follow the road back up the hill, and turn right just before you cross the rail line to head back to your car. If you had a second car you could drop it at the colliery if you wanted to save the walk.
Alternatively you can head up Kamarah Gully and on to Koombanda Ridge, and thence back to the road. If you take this exit, you could leave a second car on the Bell Rd.