The Cors y Llyn Reserve is one of several mires in the old county of Radnorshire and is located to the south of Newbridge-on-Wye. This fascinating area consists of two basins with quite different biological qualities separated by a drier ridge of peat. These hollows were carved out of the bedrock by glacial action, and the basins are largely surrounded by wet woodland with fields of grassland beyond. Cors y Llyn also boasts a small and colourful herb-rich meadow as well as an expanse of open water with emergent vegetation.
From the car park, a fully accessible linear route on grass mesh and board-walk runs for 500 metres, through gates, fields and parts of the mire - finishing at some seating. This route takes in the herb-rich meadow and an extensive area of open water before reaching the mire entrance gate. There is open access within the meadow; however within the mire enclosure itself, keep to the board-walk to avoid sinking in the very deep soft ground and keep dogs on leads at all times.