The Afon Gwy — known in English as the River Wye — is one of Britain's most celebrated and storied rivers, rising on the slopes of Pumlumon (Plynlimon) in the Cambrian Mountains of Mid Wales at an elevation of approximately 690 metres (2,260 feet) before flowing some 250 kilometres (155 miles) in a generally south-easterly direction to meet the Severn Estuary at Chepstow. Along its journey, the river passes through Builth Wells, Rhayader, Hay-on-Wye, Hereford, Ross-on-Wye, and Monmouth, straddling the border between Wales and England through much of its lower course. The Wye Valley is designated a National Landscape (formerly an Area of Outstanding Natural Beauty), and the river itself holds both Site of Special Scientific Interest (SSSI) and Special Area of Conservation (SAC) status for the majority of its length — a testament to its ecological richness and importance. Historically regarded as the most famous and productive salmon river in Wales, the Wye offers an extraordinary diversity of angling experiences, from fast-flowing mountain rapids in its upper reaches to wide, slow-moving lowland stretches in its lower course. Its major tributaries — the Elan, Ithon, Irfon, Lugg, and Monnow — contribute to a vast and varied river system that supports an impressive range of fish species and aquatic life.