From above ground it looks like just an ordinary patch of grass on a residential road in a North Bristol suburb, but behind a firmly locked entrance point in Southmead lies a unique Jurassic cave system that was once known as the city’s answer to Wookey Hole.
Plunging 200ft down through craggy rocks to a deep freshwater lake, the mysterious, twisty and potentially treacherous Pen Park Hole dates back 190 million years and has claimed the lives of at least two curious explorers in its dark past. These days it’s only authorised visitors who are allowed to venture inside this incredible, scientifically important, subterranean world, and most Bristol people have no idea it’s there.
This unique bit of ancient history under our feet caused quite a stir when it was first uncovered back in 1669 by a retired mariner called Captain Sturmy of Easton-in-Gordano. The story goes that he and an experienced miner were lowered underground on ropes and explored the natural caves by candlelight.
Read more: Timewarp Bristol shopping mall lay hidden for more than a hundred years
The miner reported that he had been frightened by an “evil spirit” down there and a few days later Sturmy suffered a violent fever and died. Just over a century later, in 1775, the Rev Tom Newman perished when investigating the hole with three companions.
The 25-year-old clergyman was trying to measure the depth of the cave while clinging onto an ash tree above, but the branch snapped and he plummeted to a watery grave in the lake. It was weeks before his body was eventually recovered.
People continued to be fascinated by the wonders of the caves, for a long time the deepest recorded in Britain. It was the first ever to be documented in this country, as well as the subject of the world’s first published cave survey in 1683.
Pen Park Hole is still regarded as a fine example of a hydrothermal system, formed when rising hot water dissolved and mineralised the rock leaving behind some stunning “dog tooth” crystals. There’s evidence of some mining activity in the caves from the 1800s, but they were securely closed in the 1870s by the then landowner to prevent accidents.
The hole vanished into myth and legend until the 1950s and 60s when the area was being assessed as a site for development. The exact position of the hidden underground caverns was located once more before they were sealed up again for another 30 years.
In 1993, as part of a local landscaping project, Bristol City Council established a new, limited route into the chambers, down a ladder inside a concrete tube. Still invisible from above, Pen Park Hole was finally reopened for approved visits through local caving clubs only.
In more recent times a rare community of blind albino freshwater shrimps - niphargus kochianus - has been found living in the lake and it’s these tiny creatures that are responsible for Pen Park Hole being designated a Site of Special Scientific Interest by Natural England, a status that now protects the site from future development.
For more information and to learn about access inside the caves visit the Pen Park Hole website. The entrance is securely locked and the site reiterates that "access has to be controlled for safety reasons".
Love nostalgia? Click here to see all the best Bristol Nostalgia stories
READ NEXT
- The tough Bristol pub where Blackbeard quaffed ale and rockers settled disputes
- Unearthed photos reveal rare scenes behind locked doors at Bristol Prison
- Forgotten moments come alive in long lost pictures from 1970s Bristol
- Wander through Bristol in the 1950s in incredible forgotten photos
Excavation reveals history of Bristol's most secret industrial site
