The reserve consists of three wildflower meadows and a large area of woodland. The reserve lies on the site of a former coal-mine and is a wonderful example of how nature can reclaim an area.
Allt Rhongyr is within the Brecon Beacons National Park, adjacent to Craig y Rhiwarth Nature Reserve and offers dramatic views of the Tawe Valley. It features a diverse mix of limestone grassland, acidic grassland and woodland and it was once the site of an iron age hillfort. The site is now managed by grazing under an agri-environment scheme.