List of Sites of Special Scientific Interest in the Brecon Beacons National Park

There are 83 Sites of Special Scientific Interest (SSSIs) within the Brecon Beacons National Park just under 10% of the over 1000 such designated areas in Wales as a whole. As elsewhere, the majority of sites of special scientific interest (also commonly referred to as 'SSSIs') in this National Park are designated for their flora and/or fauna (‘biological SSSIs’) whilst a lesser number are designated for their geology (‘geological SSSIs’). Others again are designated in respect of both interests and may be described as ‘mixed’. Natural Resources Wales is the body responsible for their designation and issuing consents for (or indeed refusing permission for) activities to take place within them. Most SSSIs are single contiguous areas though a handful comprise two or more separate parcels of land (see 'sections' column in table below).

The National Park stretches across parts of seven separate principal areas (counties or county boroughs of Blaenau Gwent, Caerphilly, Carmarthenshire, Merthyr Tydfil, Monmouthshire, Powys and Rhondda Cynon Taf) and there are SSSIs within the National Park sectors of each of them except for Caerphilly. A few SSSIs straddle the boundaries between two or three of these principal areas. Some also straddle the boundary of the National Park and may extend into other council areas such as Neath Port Talbot.https://datamap.gov.wales/maps/new?layer=inspire-nrw:NRW_SSSI#/; Welsh Government mapping portal

SSSI namePrincipal areainterestsectionsAbercriban QuarriesMerthyr Tydfil County Boroughgeological1Afon Wysg (isafonydd) / River Usk (tributaries)PowysbiologicalseveralAlexanderstone MeadowsPowysbiological1Baltic & Tyle'r-bont QuarriesMerthyr Tydfil County Boroughgeological1Black MountainsPowysbiological1Blaen NeddPowysmixed1Blorenge Monmouthshirebiological1Boxbush Meadows Powysbiological1Brecon Beacons Powysmixed2Bryn-bwch Powysbiological1Buckland Coach House & Ice HousePowysbiological1Cae Bryn-tywarch Powysbiological1Cae Cilmaenllwyd Carmarthenshirebiological1Cae Gwernllertai Powysbiological1Cae Maes-y-ffynnon Carmarthenshirebiological1Caeau Cwmcoynant Powysbiological1Caeau fferm Powysbiological1Caeau Nant y Llechau Powysbiological1Caeau Pant-y-bryn Carmarthenshirebiological1Caeau Tir-mawr Carmarthenshirebiological1Caeau Ton-y-fildre Powys / Neath Port Talbotbiological1Caeau Ty-mawr Powysbiological1Carreg Cennen Carmarthenshirebiological1Cathedine Common Wood Powysbiological1Coed Blaen-y-cwm Powysbiological1Coed Llandyfan Carmarthenshirebiological1Coed Mawr Blaen-car Powysbiological2Coed Nant Menasgin Powysbiological1Coed y Cerrig Monmouthshirebiological1Coedydd Tregyb/Tregib Woodlands Carmarthenshirebiological1Coed-y-person Monmouthshirebiological1Craig y Rhiwarth Powysmixed1Cwar Glas Quarry & Sawdde Gorge Carmarthenshiregeological1Cwm Cadlan Rhondda Cynon Tafbiological1Cwm Clydach Monmouthshiremixed1Cwm Llanwenarth Meadows Monmouthshirebiological1Cwm Taf Fechan Woodlands Merthyr Tydfil County Boroughbiological2Daren Fach Merthyr Tydfil County Boroughbiological1Dyffrynoedd Nedd a Mellte a Moel Penderyn Neath Port Talbot / Powys / Rhondda Cynon Tafmixed3Foxwood Monmouthshirebiological1Gilwern Hill Monmouthshiremixed1Gweunydd Dyffryn Nedd Powysbiological1Gyfartha Powysbiological1Henallt Common Powysbiological1Heol Senni Quarry Powysgeological1Illtyd Pools Powysmixed2Llanfihangel Moraine Monmouthshiregeological1Llanover Quarry Monmouthshiregeological1Llyn Syfaddan (Llangorse Lake) Powysbiological1Mandinam a Coed Deri Carmarthenshirebiological3Mynydd Du (Black Mountain) Carmarthenshire / Powysmixed1Mynyddoedd Llangynidr a Llangatwg, Cefn yr Ystrad a Chomin MerthyrBlaenau Gwent / Caerphilly / Merthyr Tydfil / Monmouthshire / PowysmixedseveralNant Glais Caves Merthyr Tydfil County Boroughgeological1Nant Llech Powysmixed1Ogof Ffynnon Ddu Powysmixed1Ogof Ffynnon Ddu - Pant Mawr Powysmixed1Penmoelallt Rhondda Cynon Tafbiological1Pen-y-craig goch Carmarthenshire biological1Pen-yr-Hen-allt Powysbiological1Plas-y-gors Powysbiological1Pwll-yr-wrach Powys biological2Rhos Cruglas Carmarthenshiregeological1Rhos hen-glyn-isaf Powysbiological1River Usk (Lower Usk)/Afon Wysg (Wysg isaf)Monmouthshirebiological1River Usk (Upper Usk)/ Afon Wysg (Wysg uchaf)Carmarthenshire / Powysbiological1River Wye (Upper Wye) Powysbiological1Siambre ddu Monmouthshiremixed1Strawberry Cottage Wood Monmouthshirebiological1Sugar Loaf Woodlands Monmouthshirebiological3Tir Mawr a Dderi Hir, Llwydcoed Rhondda Cynon Tafbiological1Waun Ton-y-spyddaden Powysbiological1Waun-ddu Carmarthenshirebiological1Woodland Park & Pontpren Rhondda Cynon Tafbiological3Y Gors Powysbiological1Ydw Valley & Fron Road Geological exposuresCarmarthenshiregeological5

Former SSSIs The following ceased to exist when they were superseded by the designation in 2025 of the much larger Mynyddoedd Llangynidr a Llangatwg, Cefn yr Ystrad a Chomin Merthyr SSSI.

SSSI namePrincipal areainterestsectionsCwar yr Ystrad a Cwar Blaen Dyffryn Powysgeological2Mynydd Llangatwg Blaenau Gwent / Monmouthshire / Powysmixed1Mynydd Llangynidr Blaenau Gwent / Powysgeological1

Other websites Natural Resources Wales provides a search facility for protected areas in the country on its website.

References