Swildon's Hole

Swildon's Hole is a cave near the village of Priddy in the Mendip Hills, Somerset, in south-west England. With more than nine kilometres of passage it is the longest cave on Mendip and among the best-known in Britain. It is a caving destination, not a show cave: there is no lighting, no paths and no ticketed guided tour.

What kind of cave is it?

Swildon's is a swallet cave, meaning a surface stream sinks underground and carries on through a cave passage. The Mendip Cave Registry lists a length of about 9,146 m, a depth of 167 m and an entrance altitude of around 238 m. Cavers first descended it in 1901, which makes it one of the earliest systematically explored caves in the country. It was later found to connect with neighbouring Priddy Green Sink, and the whole system sits within the Priddy Caves Site of Special Scientific Interest.

What is underground?

After a small entrance the stream leads steeply down a wet passage. Expect cold water, and know that levels rise fast after rain. Further in comes the first sump, a section completely flooded with water. Beyond it the passages flatten into broad loops. Deeper in, more sumps require diving equipment, and exploration has pushed as far as the twelfth.

Can visitors go in?

Not as ordinary sightseers. The cave is popular with cavers, but it calls for experience or a leader who knows the system. You need a caving suit, a helmet with a headlamp and warm layers underneath. A small fee is paid at a house by the footpath, and cavers change in a barn on Priddy Green. Beginners should go through a local caving club or a commercial adventure operator. Check the weather before any trip, since rising water can cut off the way out. The dive line at the first sump has been reported damaged at times, so ask local clubs about current conditions.

How do I get there?

Priddy sits on the Mendip plateau, roughly 10 km from Wells and about 20 km from Bristol. A car is the practical choice, as public transport to the village is limited. The entrance lies a short walk beyond the village along a path from the road.

What else is nearby?

The Mendip Hills form a National Landscape with gorges, caves and open hills. Other caves of the Priddy group, including Eastwater Cavern, Hunter's Hole and St Cuthbert's Swallet, each have their own character and difficulty. For a gentler day, walk the plateau or visit Wells for its cathedral and local museum.

Frequently asked questions

How long is Swildon's Hole?

The Mendip Cave Registry gives about 9.1 km of passage and a depth of 167 m. It is the longest cave on Mendip.

Is there an entry fee?

Yes, a small fee is paid at a house beside the path to the cave. Bring cash and confirm current rules with a local club.

Is it suitable for beginners?

Only with an experienced leader and for a short trip. The cave is wet and the water level depends on the weather, so it is not a place for an unprepared solo outing.

Is the cave protected?

Yes. Swildon's Hole is part of the Priddy Caves SSSI, so damaging formations or disturbing wildlife is not allowed.