A 110m entrance shaft leads to climbs down to a small chamber. The cave begins as a low crawl which enters the main stream pasage after 10m. Downstream is sump 1 that can be passed in dry conditions to the permanent sump 2 that closes down. Upstream the passage rises to a 5m high rift that requires traversing at roof level to progress until a chamber is reached. From the chamber the way ahead is blocked by miners deads.

In 1978, the Shaft Capping Programme led by NKC Partnership capped several shafts at the Bog Mine, including the Bog Issa Shaft SJ 2058 5721, the ladder shaft SJ 2050 5721, the Bog Old Engine Shaft SJ 2069 5709, and the area around the old Bog farm SJ 2085 5705.

The Westminster Vein, running east to west through lands owned by the Duke of Westminster, was worked extensively from the 18th century onwards. The vein was initially worked at the eastern end by the Nant Mine (SJ 1977 5774) and extended as far as the Llanarmon Mine (SJ 2170 5680). While some 18th-century workings along the vein were limited to open workings on the limestone outcrops, much of the earlier mining evidence has been lost due to later, more extensive operations. During the 19th century, the Bog Mines worked the vein over several periods, with significant extensions including the New Shaft, Mary Ann Shaft, and Bog East.

Controlled by GCC/NWCC/