The aim of this site is to provide descriptions, personal impressions, the location and many photo's of the majority of the known caves on the Isle of Portland, Dorset.
Caving on Portland is somewhat of an acquired taste. The caves consist of a mixture of phreatic tunnels usually requiring crawling, and rifts which usually require thrutching. The largest caves exist where various rifts and tunnel intersect. Chambers or walking passage is rare and active stream ways non-existent. Formations are not hugely common, but where they can be found are often magnificently coloured consisting of various shades of yellow & orange. Other features include moonmilk and some impressive fossils.
If you decided to head to Portland for a spot of underground fun the most notable caves are listed below. The rest are most definitely collectors pieces best described as 'scrote holes'. Despite this, much fun can be had scrambling / walking around the island poking in and out of these.
1. Ariel Cave (AKA Blacknor Hole) round trip or the Ariel to Sandy through trip
2. Grove Cliff Caves (AKA Flagpole)
3. Sandy Hole (either Sandy entrance or via Sharbutts Rift)
6. Fossil Cave (AKA Rubbish Dump)
7. Windy Dig
8. Persil Rift
10. Cherty Rift
A number of Portland's caves have been formally surveyed and most of these were published in 'The Caves of the Isle of Portland' (see below). Most caves however are simple and do not require a survey to explore. Where a survey might prove useful I have provided a sketch survey. I have drawn these by simply creating an overlay on Google Earth, marking known points on the surface such as entrances, cliff lines and paths, and then joining the dots from memory of where the passage roughly goes. These are not measured, unlikely to be accurate but will be more than sufficient to follow underground. Please feel free to print and take with you.
The naming of Portland's caves and the passages within is often confusing. A number of different groups from outdoor education centres, scouts, local cavers and even the local yobs who like to drink beer underground have come up with their own or confused those specified by the original explorers. Some of these names have become more common place than the original ones and therefore must be noted. To the best of my knowledge I have referred to each cave or passage by the name originally given whilst providing the alternatives under 'also known as'. I am grateful for the assistance provided by Nigel Graham with respect to this.
Further information including detailed descriptions, history of exploration, surveys and geology can be found in the book 'The Caves of the Isle of Portland' by Mike O'Connor and Nigel Graham. Unfortunately the book is now out of print, however an updated digital version is available on the MCRA website:
Alternatively, feel free to contact me: email@example.com.