Ogof Ffynnon Ddu

Ogof Ffynnon Ddu
Location	Upper Swansea Valley
Coordinates
Depth	274.5 metres (901 ft)
Length	50 kilometres (31 mi)
Height variation	320 metres (1,050 ft)
Discovery	South Wales Caving Club 1946
Geology	Limestone
Entrances	3
Access	Ogof Ffynnon Ddu Management Committee - see South Wales Caving Club website for details
Translation	Cave of the Black Spring (Welsh)
Cave survey	[1]

File:Inside Ogof Ffynnon Ddu.jpg

Part of the interior with a terraced cascade and three standing and climbing cave explorers wearing safety equipment

Ogof Ffynnon Ddu (Welsh for Cave of the Black Spring; also known as OFD) is a cave under a hillside in the area surrounding Penwyllt in the Upper Swansea Valley in South Wales. At 274.5 metres (901 ft) deep and 50 kilometres (31 mi) long, it is the deepest cave in the UK and the second longest in Wales.

OFD was discovered in 1946 through digging by Peter Harvey and Ian Nixon, members of the newly formed South Wales Caving Club. Major extensions were discovered in 1967. The system is famous for its intricate maze-like structure and its impressive main stream passage. It forms the Ogof Ffynnon Ddu National Nature Reserve.

One of the largest cave systems in Britain, the caves and tunnels of Ogof Ffynnon Ddu weave a long and tortuous path beneath the Tawe Valley. Deep underground, an assortment of specialised wildlife has developed including cave shrimps and the pale blanched trout endemic to pure underground fresh watercources with sufficient plankton. Deep cracks in the vast expanse of stony moorland above provide habitats to plant life, including the lily of the valley and wood anemone.

External links

• Virtual tour of the cave
• South Wales Caving Club