Coober Pedy, known as the Opal Capital of the World, is 529 miles northwest of Adelaide in South Australia and 427 miles south of Alice Springs in the Northern Territory.  Opals were first discovered here in 1915 and today 3,500 people, from all over the world, live in this frontier town.   What makes Coober Pedy so interesting is that half of its people live underground to escape the summer heat.  There are homes, stores, restaurants, bars, a museum and  churches that are all underground!  Surrounding the town are open mine shafts with sun-bleached mounds of earth.   While visiting Coober Pedy, you can go "noodling", which is the local expression for looking for opals, take some tours - town, desert, mine or even a mail-run, or visit an underground home.  The highlight for most people is a stay at the Desert Cave Hotel in one of their underground rooms. Just click on the Desert Cave button above to see this unique hotel in the middle of the South Australian Outback.