A cave which is separated from Agen Allwedd by only 6 m of dangerous boulder choke. 500 m of crawling enters large breakdown style passages, including, at one point, the largest passage in Britain. Many areas are well decorated with helictites, most notably the Blue Greenies, the Antlers, the White Company and Where The Sun Don't Shine. The cave contains a long sump to the resurgence at Pwll-Y-Cwm and Elm Hole. One inlet streamway reaches the seventh hour sump, the most remote sump in Britain. The Prices Old Dig entrance enters the cave via a flood prone U-tube bypassing the normal entrance crawl (making a 4 hour through trip). The through trip from here to Pwll-Y-Cwm is the second deepest cave through trip in Britain at 203 m (about 4 m of passage, including the U-tube, is partly artificial, bypassing a choke). For descriptions, contact the Chelsea Spelaeological Society or me, or see the dedicated Daren Cilau site (includes an almost complete survey).
Note that the cave is also sometimes incorrectly referred to as Ogof y Daren Cilau.