Contains most of the long cave systems. Almost no potholes. Cave systems are usually well decorated and are dominated by large passages, often with significant riverways. Many local drainage systems, often very immature. Total combined cave length is the second highest of all regions.
Almost all major caves are within the Brecon Beacons National Park, with the exception of Tooth Cave which is within the Gower Peninsula Area of Outstanding Natural Beauty and Otter Hole which is within the Royal Forest of Dean National Forest Park.