Pontsticill Reservoir lies just north of the town of Merthyr Tydfil in South Wales, United Kingdom and on the edge of the magnificent Brecon Beacons. It is capable of holding 3,400 million gallons of water behind its' 110 foot embankment which was completed in 1927 it covers 102 hectares of land. Part of the 2011 film Submarine was filmed on the reservoir walkway.