Hay-on-Wye in Hay is a sub-office of Hereford, and therefore although in Wales has an English postal address, being part of the HR3 postcode. Hay-on-Wye is a Welsh community with a Town Council. Its boundary follows the English border/Dulas Brook from the River Wye southeastwards for just over a kilometre, turns south-west to a point just south of Oakfield house, thence north to Greenpit Farm and north westwards, enclosing the Hay Showground and meeting the National Park boundary near the B4350, Brecon Road. From this point, it follows the National Park boundary to the River Wye and the river back to
Wye Valley Walk Hafren, having passed within viewing distance of the source of the River Wye on Plynlimon near Aberystwyth, a total of . The Wye Valley Walk is marked out by circular yellow waymark arrows, finger posts, and signs showing the path's logo, a leaping salmon. Most of the route follows Public Rights of Way. Some parts are permissive paths where owners have agreed for them to be used. Parts of Plynlimon are open countryside in which there is a right to roam established by the Countryside and Rights of Way Act 2000. The route passes through Chepstow, the Wye Valley AONB,