Hafren Forest lies north-west of Llanidloes, an ancient market town in Mid Wales. The forest covers around 40 square kilometres, and consists mainly of pine and spruce trees. It takes its name from the Afon Hafren which rises in a deep peat bog approximately 800 metres outside western boundary of the forest, high on the slopes of Pumlumon, the highest …Hafren Forest lies north-west of Llanidloes, an ancient market town in Mid Wales. The forest covers around 40 square kilometres, and consists mainly of pine and spruce trees. It takes its name from the Afon Hafren which rises in a deep peat bog approximately 800 metres outside western boundary of the forest, high on the slopes of Pumlumon, the highest mountain in Mid Wales.