The Pentland Firth between Orkney and mainland Scotland has been described as the "Saudi Arabia of tidal power" and may be capable of generating up to 10 GW although a more recent estimate suggests an upper limit of 1.9 GW. In March 2010 a total of ten sites in the area, capable of providing an installed capacity of 1.2 GW of tidal and wave generation were leased out by the Crown Estate. Several other tidal sites with considerable potential exist in the Orkney archipelago. Tidal races on the west coast at Kylerhea between Skye and Lochalsh, the Grey Dog north of Scarba, the Dorus Mòr off Crinan and the Gulf of Corryvreckan also offer significant prospects.