(S) From YHA Danywenallt head towards the dam and disused railway, practically south from the hostel. Cross the old railway, now a bike route and follow the path upwards to a waterfall and into the woods. When the path meets a track turn left out of the woods then take a path right up the field to the road that leads to Pantywenallt. Here, turn right at the cattle-grid then take the path left heading east to a small wood. Continue on the Usk Valley Walk to the canal. Cross the bridge and follow the towpath along the canal to Llangynidr.
(1) When the canal goes under the B 4560 take the path up to the road and turn left. The road gets progressively narrower as it approaches Llangynidr Bridge (also known as "Coed-yr-Ynys Bridge"), an early 18th-century bridge. It's worth popping down to the riverside to get a better view of the fine structure, probably better downstream as there are fewer trees. Fortunately, there are some pedestrian passing spaces along the bridge as there isn't much room for the cars. The route continues along the road, ignoring a path going off to the right and going straight on at a crossroads and past Pant-y-beili Farm. At the next junction, don't go on to the A 40 but take the small road off to the left to Carner Ways Farm. Head west across the fields to some houses but skirt around them north then west to reach Darren Road. Turn right along the road and down into Bwlch.
(2) When you reach the A 40 again, turn right at The New Inn then left after The Star Bunkhouse (signposted to a chapel). The path heads across to a minor road, turn right then left to follow the signs indicating the route uphill past a white farm building. The route climbs steadily up to a cairn, heading north-east, then heads further north to another two cairns going over Cefn Moel. Cross over a couple of paths to reach another two cairns above Maesclythan Wood down to the left. At the next crossing of paths, take the right hand route to head down to Blaen-y-cwm-uchaf Farm. Ignore a path off to the right before the farm, rather pick up the track after the farm leading to Blaen-y-cwm-isaf Farm. From here, keep heading south along the local road for about a mile. When the lane leaves the woods and you see a footpath sign next to a couple of metal gates, turn left over the style and head over the fields to join another local road and turn left. Go over the bridge crossing Rhiangoll and into Cwmdu.
(3) Go straight over the A 479 at the Farmers Arms and continue along the lane past St. Michael & All Angels Church. Keep going up the lane for about half a mile, ignoring a track that comes in from the right until you reach Pen-cae-crwn Farm. Here turn right to head up another lane to a T-junction. Take the right fork heading up to Vedw Farm and the woods beyond. Once past the woods, the track bends left towards Llewenau farm. Just before the farm, the path bears off right to climb up towards Pen Allt-mawr. However, after about 50m the paths turn right again to head southeast along Llewenau Draw, crossing a stream and following the hillside along the field boundaries to Cwm Mawr. Continue around the base of Pen Cerrig-calch to enter a wood, where the path turns south away from the mountain. Going downhill from the woods, the track goes past Twyn farm and continues down to another farm at the head of a lane. This takes you right the way down to the A 40 and into Crickhowell (Crughywel).
(4) Turn left along the road past the school and turn right into Everest Drive. Follow the road round to the left and through the hedge at the end to go past the High School. This will bring you out onto the A 4077 New Road at which you turn right past St. Edmund's Church on the left and down to the River Usk (Afon Wysg). Once over the Crickhowell Bridge turn left along the A 4077 for about 50m, ignoring the first turn off to the right (indicated Llangattock) in front of a grey-coloured house The Vine Tree. Take the lane between two older houses that leads through woods towards Nant Onneu-fach and Park Farm. At the end of the woods turn left along a track then second right (to avoid the farm) heading up to a small wood. At the other side of the wood, the path crosses the canal and heads south to Hen Castell, meeting a lane at a wooden style. Head straight forward along the lane to Ty Mawr Farm. Turn right up to the farm then left just before the buildings. The track bends to the right and climbs up the hill to Laswern-Isaf Farm. Keep heading uphill until the track turns 90º right to go to Laswern-fawr Farm. Take the path off to the left to reach YHA Llangattock Bunkhouse.(E)