The southern fringe of the Brecon Beacons National Park consists of a long belt of outcrop lime stone which has created a highly distinctive environment characterised by wooded gorges, caves, swallow holes, and waterfalls. This intriguing landform is most distinct in the locality known as "Coed Y Rhaeadr" which translates as "Wood of the Waterfalls" but is referred to locally simply as "Waterfall Country". Waterfall Country is situated in a triangle formed by the villages of Hirwaun, Ystradfelte, and Pontneddfechan. Waterfall country includes the head waters of the rivers Nedd, Mellte, Pyrddin and Hepste. These rivers drain the old red sandstone mountain ranges of the Fan’s in the north and travel south through the deep V shaped wooded valleys the rivers have formed in the carboniferous limestone of the southern belt of the national park. In addition to being part of the national park, waterfall country is officially designated as a site of special scientific interest containing over 200 species of mosses, liverworts, and ferns.

There are particular dangers attached to walking in the waterfall country. The footpaths take you along and above deep valleys. It is common place to find yourself walking on a narrow slippery footpath with a steep dangerous drop on one side. Avoid walking to the edge of paths or waterfalls. Take especial care when viewing waterfalls as the sheer beauty of the waterfall may be distracting and lead you into danger. The valleys are heavily wooded and the leaves that fall during the autumn have a tendency to linger on the surface of the ground throughout the year. Consider also that rock may outcrop on sections of the footpaths surfaces which are often wet and therefore especially slippery. It is no exaggeration to say that one should take particular care when the walking in waterfall country and be mindful of the fact that many accidental deaths have occurred here. Walking boots with good gripping soles are essential. Having said that waterfall country is one of the most rewarding experiences for the walker that to be found in any National Park in England and Wales.