Lightning Ridge is a town in north-western New South Wales, Australia, in Walgett Shire, near the southern border of Queensland, about six kilometres east of the Castlereagh Highway, and is served in commercial activities by the town of Walgett, some 75 km to the south. Lightning Ridge is a flourishing tourist town with numerous caravan (camper-trailer) and camping parks, the previously very rustic Diggers' Rest pub (which has burned down for the third time) and a well-appointed bowling club with its eight artificial-grass bowling greens. Temperatures in summer can reach into the high 40s Celsius, but below ground the temperature remains continually at around 22 degrees, year round. The Lightning Ridge area is a world-renowned centre of the mining of black opals and other opal gemstones. Lightning Ridge has the largest known deposits of black opals in the world. The name Lightning Ridge is said to have originated when in the 1870s some passers by found the bodies of a farmer, his dog and 200 sheep which had been struck by lightning.