Pen Park Hole is a large cavern situated underground, at the edge of Filton Golf Course. The cavern was discovered accidentally in the 17th Century and the first descent was made by Captain Sturmy in 1669. The entrance is adjacent to the Southmead and Brentry housing estates of north Bristol. Access is tightly controlled by Bristol City Council. It was scheduled as a Site of Special Scientific Interest in August 2016 on account of its geological origins, and its cave invertebrate community including the cave shrimp , which is normally known as a spring seepage or chalk aquifer species.