The upper reaches flow through a dramatically steep sided, rocky valley in the heart of the Black Mountains.

Despite the Welsh translation of its name implying an easy paced flow, the Honddu is an archetypal mountain stream, rushing over the bedrock and boulders, through gutters and into deep, inviting pools.

At just over ½ mile in length, Half Moon is an outstandingly beautiful remote beat. Access and wading are comparatively straightforward and all but the odd corner is fishable with an 8ft rod.