The top of the catchment. A rarely paddled section that is quite serious due to the amount of scouting and difficult portaging required around Rob Roy Falls and the Silent Pool.
The section down to Rob Roy Falls is quite wide and shallow but includes some short basalt constrictions. The spectacular 90m Rob Roy Falls is portaged on river-right. Below the falls, the rock changes into more of a classic Nymboida-style with many 3-4m drops and some technical trees encountered. 
At the confluence with Deer Park Creek another major feature is reached. The Silent Pool is a freak of nature unlike any other on the Dorrigo Plateau and is folklore legend amongst the Dorrigonians. It is named because the Nymboida River allegedly goes underground and bubbles up silently in the pool a hundred metres downstream. In reality, it is a deep, super tight, log-jammed, chock-stone filled chasm that is best portaged on river-right. 
Some maps call the section of the Nymbo from Waterfall Way ‘Coutts Water,’ with the Nymboida commencing at the junction with Deer Park Creek.  
Popularity:★
Quality:★★★★
Reliability:★★
Grade:IV-
Length20km
Elevation and average gradient1170m at put-in, 690m at take-out, 24m/km average
Paddling time:8+ hours. First descent team took two days.
Gauge and level:Visual check at put-in or take-out. As a rough guide there should be a minimum of 10cm of water over the causeway at upper Harness Cask (the take-out). Estimated to be 3m+ on the Nymboida@Nymboida electronic gauge.
Shuttle:Easy (2WD). 1 hour each way via Armidale Road, Tyringham Road and Harness Cask Road. 
Put-in:Bridge over ‘Coutts Water’ on Waterfall Way, approximately 30km west of Dorrigo.
Take-out:Harness Cask, where Harness Cask Road crosses the river, approximately 6km west of Tyringham Road. 
Maps:Map 2 Nymboida River- Waterfall way to Tyringham
Hernani 1:25,000
Dorrigo 1:25,000