Longwood Swallet

Longwood Swallet is a cave in the Carboniferous limestone of the Mendip Hills, close to the village of Charterhouse in Somerset and a short distance from Cheddar. It is a site for experienced cavers rather than a visitor attraction: the entrance is locked and entry runs through a permit system.

What is Longwood Swallet?

The cave lies in Longwood Valley and forms part of the Cheddar Complex SSSI. It once had its own protected status together with its neighbour August Hole, and the two are often treated as a single Longwood/August system. The wider Cheddar Complex covers more than 441 hectares and has been protected since 1952.

Surveyed passages total roughly 1.65 km, and the system drops about 175 m. A natural shaft in the valley floor opens onto a tangle of passages and several large chambers, formed along faults and widened by rockfall.

Who found it?

Pupils from Sidcot School discovered the cave in September 1944. The Stride brothers drew up a survey in 1946, published by the University of Bristol Spelaeological Society (UBSS). A later UBSS plan from 1948 shows Longwood Swallet and August Hole together.

Can you go in?

Access is managed by the Charterhouse Caving Company (CCC Ltd), which began as a committee set up at the request of Bristol Water, the former owner of the land. Today the Somerset Wildlife Trust looks after the ground, and the CCC works with it to keep the caves open to cavers. Permits and keys are obtained through member clubs such as UBSS. Check current rules with the CCC and the CSCC access guide before planning a trip.

This is not a beginner outing. You need caving experience, rope gear and proper preparation. First-timers are better served by the show caves in nearby Cheddar Gorge.

What are the risks?

The cave floods often. A flood pulse can also arrive when Bristol Water switches off its pumps at the Charterhouse spring, because the water then runs down the stream into the cave. Check the weather forecast and water levels before descending.

What else is nearby?

Charterhouse has other Mendip caves, including Rhino Rift, dug open by Wessex Cave Club members in 1971. Walkers can head for Cheddar Gorge and the surrounding hills. A path through Longwood Valley has been closed because of ash dieback, so check Somerset Wildlife Trust notices before setting out.

Frequently asked questions

Where is Longwood Swallet?

Near Charterhouse in the Mendip Hills, Somerset, England, a few kilometres from Cheddar.

Is the cave open to tourists?

No. The entrance is locked and the Charterhouse Caving Company controls access. Permits go to experienced cavers through member clubs.

How deep is the cave?

About 175 m deep and around 1.65 km long.

When was Longwood Swallet discovered?

In September 1944, by schoolchildren from Sidcot School.

Is it safe to enter after rain?

No. The cave floods, so check the weather and water levels first.