|Location||Cheddar, Somerset, England|
|Altitude||128 metres (420 ft)|
The cave was first dug out in 1951 by members of Wessex Cave Club, and further progress was made in 1965 when "Moonmilk Chamber" was reached with the use of blasting. "Grand Gallery" was discovered in 1969, "Topless Aven" in 1970 and "Golgotha Rift" in 1973. 
In September 2012, after four years' work clearing a 100 metres (330 ft) long passage, a group of diggers broke into a new chamber which was found to be 30 metres (98 ft) high and 60 metres (200 ft) long. Prior to the discovery, the largest void under the Mendip Hills was thought to be "Main Chamber" in GB Cave, which is 23 metres (75 ft) high.
Before the find in 2012, the cave was already noted for a number of fine formations, and the newly discovered chamber, which has been named “The Frozen Deep”, contains pure-white pillars 5 metres (16 ft) tall, as well as many stalagmites and stalactites.
The possibility of a connection between Reservoir Hole and Gough's Cave, one of the show caves in Cheddar Gorge, has been raised, as the two caves are in close proximity. The stream in Reservoir Hole emerges only a short distance down Cheddar Gorge.
- "Access Guide". Council of Southern Caving Clubs. Retrieved 28 September 2012.
- Irwin, David John; Knibbs, Anthony J. (1999). Mendip Underground: A Cavers Guide. Bat Products. pp. 115–116. ISBN 0-9536103-0-6.
- Barrington, Nicholas; Stanton, William (1977). Mendip: The Complete Caves and a View of the Hills. Barton Productions/Cheddar Valley Press. p. 127.
- "Cheddar cave 'biggest in Mendip Hills'". BBC News online. 7 September 2012. Retrieved 16 September 2012.
- "In Pictures: Finding the 'biggest cave' in the Mendips". BBC News online. 11 September 2012. Retrieved 16 September 2012.
- "Somerset cavers spend their retirement tunnelling into the Mendips". BBC News online. 12 September 2012. Retrieved 16 September 2012.
- Hendy, Philip (October 2012). "Huge new cave found in Cheddar Gorge". Mendip Times 8 (5): 75.
- Mendip Cave Registry and Archive: Reservoir Hole (not yet updated for the newly discovered chamber)
- Geograph: photographs of parts of the cave known prior to 2012 discovery
- Rose, David (29 December 2012). "Inside the Frozen Deep: Mail on Sunday man is first to be pictured in Britain's biggest cave recently discovered below Cheddar Gorge". Mail Online. Retrieved 30 December 2012. (map of Reservoir Hole cave)