Boxing Day, a local walk.
In the past, forestry operations in Harptree Woods, Mendip channelled surface water into naturally occurring sinkholes. The drainage for these sinks is localised and there are several springs along the flank of Garrow Bottom, including Garrowpipe Spring, where the water re-emerges to flow into Molly Brook.
I had a tentative poke into this sink several years ago but gave up due to the instability of the small chamber gained. It has since slumped and filled in with debris.