Britain's second longest cave. A short but low and wet entrance series leads to many kilometres of large breakdown passage, most having a floor of slippery boulders making the cave very tiring. The large passages are separated by short crawls, traverses and chokes. The streamway is comparable to that of Agen Allwedd being of a relatively easy nature. Being a relatively new discovery, several areas still have the potential for significant finds. Many areas of the cave contain stunning displays of calcite decorations, the most notable sections being about 3 to 4 hours in at a good speed. In the same area are the second and third largest passages in British caves. This cave was known as "Britain's fastest growing cave" with over 20 km of passage found within the first month of exploration. The cave has the second longest overland length of any cave in the British Isles, with a tip to tip distance of 4.889 km, which was the British record until the end of 2011.
Ogof Draenen and its access arrangements are managed by the Pwll Du Cave Management Group. For access information, a description, photos and loads more, see the Draenen description pages. Alternatively, see the quick overview map.
The last officially quoted length was 66.12 km, but the actual length of the cave is now nearer 70 km (due to the amount of passage found since the last official count). From about 1996-1997 until the end of 2011 Ogof Draenen was the longest cave in the British Isles, but this was not realised until mid-2010, when the Three Counties System surveyors updated their estimates for the length of that system. At the end of 2011, the Three Counties System once again took the title, as well as the record for longest overland length.