The Ogof Ffynnon Ddu (meaning "The Cave of the Black Spring") National Nature Reserve (NNR) is named in reference to a vast cave system discovered in 1946. It's a labyrinthine 300m/1,000ft-deep underground world of caverns and cascades, stalagmites and stalactites, passageways and potholes. Its extent is even more impressive, the overall length of cave passage is in excess of 30 miles. Managed by Natural Resources Wales, the reserve itself lies within the Ogof Ffynnon Ddu- Pant Mawr and Ogof ffynnon Ddu Sites of Special Scientific Interest (SSSI). The SSSI designation denotes an area with protected features - in this case, mostly geological features, in particular, a number of caves and some surface Limestone features. However some of the wildlife that inhabits this rocky terrain is also special. The SSSI legislation underpins the the NNR status.
Above Ground - The reserve, situated at between 310m to 540m (1015 ft to 1770 ft) above sea level, is one of Wales' most exhilarating NNRs, with breathtaking views across South Wales and the Brecon Beacons. The terrain is a mixture of rocky outcrops and tufty moorland - with few obvious paths. But don't be put off, for Ogof Fynnon Ddu (OFD) is immensely rewarding for those who take the time to explore it fully and appreciate its compelling character.
Below Ground - Access to the caves is confined to experienced cavers only. This is due to to the SSSI designation and a legal obligation to protect the SSSI from damage. Information for cavers can be found by following the "The Cave" link above. There is underground access for non-cavers just across the valley at the National Showcaves Centre, Dan-Yr-Ogof (www.showcaves.co.uk), one of Wales' most popular tourist attractions, part of which is an NNR in its own right.
Fforest Fawr Geopark
OFD is in the heart of the Fforest Fawr Geopark, designated by the United Nations Educational, Scientific and Cultural Organisation (UNESCO) in 2005. The Fforrest Fawr (Great Forest) Geopark - the only example in Wales and one of five in the UK - covers much of the western Brecon Beacons Nation Park, from the moors and mountains of Fforrest Fawr east of OFD to the Black Mountain in the west.