Upper Flood Swallet

Upper Flood Swallet is a cave near the village of Charterhouse in the limestone Mendip Hills of Somerset, England. It ranks among the most richly decorated caves in the region, yet it is no casual tourist stop: the entrance is locked and visits happen only with an approved leader.

What is Upper Flood Swallet?

A swallet is a spot where surface water sinks underground, and this one was first known as Blackmoor Flood Swallet. The great flood of July 1968 washed its entrance open, which explains the name, and the first exploration followed on 3 October that year. The cave lies within the Cheddar Complex SSSI, a protected site in carboniferous limestone.

What lies underground?

Exploration advanced through decades of patient digging, with breakthroughs in 1971, 1972, 1985 and 2006. The last one, by Tim Francis and Julie Hesketh, led into a chamber called the Departure Lounge and roughly two kilometres of further passage. The system now exceeds 4 km in length and reaches a depth of about 110 to 129 m, depending on the source and survey date. Its reputation rests on delicate, abundant formations, including the passage known as Neverland.

Can you go in?

Yes, but only on an organised trip. The entrance is locked, and the Mendip Caving Group manages access at the landowner's request. Parties are kept very small and led by a club warden, because the formations are easily damaged. Requests go to the club secretary. Rules can change, so confirm them directly before planning anything.

How do you reach the area?

Charterhouse sits on the Mendip plateau, within the Mendip Hills National Landscape. It is an easy drive from Bristol and Wells. You cannot visit the cave itself without permission, but footpaths nearby cross heathland and old mining ground, including remains of the lead workings that made Charterhouse known.

When to go and what to expect

The cave floods, so trip dates depend on weather and water levels. The route is physically demanding, with tight sections, climbing and mud, so you need caving experience, a suit, a helmet and reliable lighting. If you lack that background, the show caves at Cheddar or Wookey Hole are a better choice.

Frequently asked questions

Is Upper Flood Swallet open to the public?

Not as a commercial attraction. The entrance is locked, and the Mendip Caving Group arranges led trips.

Where does the name come from?

The July 1968 flood opened the entrance, and a swallet is a place where water disappears underground.

How long is the cave?

It has over 4 km of passage after the 2006 discoveries. Quoted depths range from about 110 to 129 m.

Is it the only cave nearby?

No. Mendip has many, such as Longwood Swallet, Rhino Rift and GB Cave, each with its own access rules.