Otter Hole

Location
Grid Reference: ST 5258 9615

Altitude: 5m



Access
A key is required as the cave is gated. Access is administered by Royal Forest of Dean Caving Club on behalf or the land owner. All trips are led by a guide. Contact details for the bookings secretary and a calendar with available dates are on the club website. In general, access is only attempted during the summer months due to unpredictable (and high) water conditions during the winter.

Description
Length: 3.4km

This cave is not strictly in the Forest of Dean as it lies on the Welsh side of the River Wye. However, its proximity to the Forest and relative isolation from the other Welsh caving areas has seen it "adopted" by the Forest area. It was, in fact, largely discovered and explored by Forest based cavers.

The cave boasts some unusual features;

Firstly, there is a tidal sump which blocks access to the cave for approximately three hours either side of the local high tide on the Wye estuary - the entrance being just a few metres from the riverbank. The entrance series is extremely muddy due to regular floodings with muddy esturine water.

Secondly, the huge calcite bosses of the type seen in areas such as the Hall of the Thirty are unknown elsewhere in the UK, on a scale more usually associated with continental caves. There are copious other calcite formations throughout the further reaches of the cave which are also extremely fine.

It is due to these factors that the guide system is in place - to protect both the cave and the cavers.



History
The cave was first explored by Gloucester SS and RFDCC in 1970. Major extensions were made, following digging, in 1974 and 1975.