Tween Twins Hole, also known as Fester Hole, is a cave in Burrington Combe, Mendip, UK.
It was discovered by members of the Wessex Cave Club in 2016 after many years digging at the site. The cave is designated a SSSI (Site of Special Scientific Interest) and was gated soon after its discovery with the permission and encouragement of the landowner and English Nature to preserve it for future generations.
A leader system is now in place and trips to the cave can be organised simply and easily via this website. If you would like to visit the cave please use the contact form on this site. Trips to the cave are limited to three cavers plus the leader and a maximum of one trip per calender week is allowed. The cave operates a closed season from 31st October to 1 April each year to protect hibernating bats and to avoid bringing mud from the original dug entrance into the cave.
Existing bookings can be viewed on the Bookings Calendar so please avoid requesting a week (Monday to Sunday) that already has a booking recorded.
A list of the guidelines for visiting cavers can be found here.