Underground homes of Coober Pedy, Australia

Coober Pedy is a small town in the middle of the desert in Australia.

The land is dry and dusty. People dig for shiny stones called opals. Many people live in homes inside the hills!

Coober Pedy is a town in central South Australia, about 850 kilometers north of the city of Adelaide, on the Stuart Highway. It sits on the edge of the Great Victoria Desert, and the land around it is dotted with mine shafts and piles of dug-up rock from opal mining.

Opals are gemstones that flash with many colors. Britannica says most of the world's opals come from the mining field here. But Coober Pedy is famous for something else too: many of its homes, and even some churches and hotels, are built underground.

Coober Pedy is a town and opal-mining field in central South Australia, about 850 km (530 miles) north of Adelaide on the Stuart Highway; its mining site lies in the Stuart Range on the edge of the Great Victoria Desert. Britannica reports that most of the world's total opal production comes from the field; the town's tourism association calls it the "Opal Capital of the World" and says the landscape around it is often described as moon-like, dotted with shafts and mullock heaps (piles of waste rock).

The District Council of Coober Pedy acknowledges the Antakirinja Matu-Yankunytjatjara people as the traditional owners of the land. The council's history notes that for thousands of years Aboriginal people moved through this desert, with the availability of water determining where they could be. Today the town is best known for its dugouts: homes, and other buildings, cut into the hillsides.

In summer, Coober Pedy gets very, very hot.

On winter nights, it can be cool. But under the ground, the rooms stay about the same all the time. Not too hot, and not too cold!

During the hottest three or four months of the year, temperatures in Coober Pedy often climb as high as 52 °C. To escape that heat, many residents build their homes below the ground.

NASA's Earth Observatory reports that inside the underground homes, the temperature stays almost the same all the time, at about 23 °C. The town's tourism association explains that miners soon found living underground helped in two ways: it kept out the summer heat and the cool desert nights of winter.

Britannica gives the reason directly: to escape temperatures that often climb to 52 °C (125 °F) during the hottest three to four months of the year, residents often build their dwellings below ground. The town's tourism association adds the other half of the desert climate: miners discovered that living underground spared them both summer heat and winter's cool desert nights.

The same association states that the rooms maintain an even temperature of 19 to 25 °C day and night throughout the year. NASA's Earth Observatory (2023) gives an almost constant 23 °C and calls underground living low-energy, low-tech climate control through passive cooling: the rooms are dug out of soft, porous bedrock, and ventilation shafts run up to the surface to bring in fresh air and let moisture out.

A home dug into a hill is called a dugout.

It has rooms, like any other home. The walls and ceilings are made of rock. Some families even dig tunnels to join two homes together!

Homes underground in Coober Pedy are called dugouts. Most are not dug straight down from a shaft. Instead, they are dug sideways into the hillsides.

The ground in Coober Pedy's hillsides is stable enough for rooms with wide ceilings. Some families buy the home next door and dig a tunnel to link the two, or even three or four. A few large dugouts spread across up to 450 square meters underground.

Most dugout homes, according to the tourism association, are excavated horizontally into hillsides rather than dug from vertical shafts. The hillside ground is stable enough to allow large ceiling spans, and it is not unusual for a mining family to buy an adjoining property and tunnel through to link two dwellings, or even three or four. The largest, which the association calls mansion-style, extend to 450 square meters underground.

The idea's origin is uncertain. The association says it is believed that soldiers returning from the trenches of France after the First World War introduced underground living, and that the homes became known as dugouts. Underground building is not limited to homes: Britannica notes that churches and other buildings, including hotels, are below ground too, and that they have become a tourist attraction. Because so many buildings are partly or completely underground, the association recommends that visitors use a map or guide.

In 1915, a boy named Willie found opals here.

Soon miners came to dig for more. A town grew up. Its name, Coober Pedy, comes from an Aboriginal phrase.

In February 1915, a boy named Willie Hutchison found opal here. He was part of a group led by his father that had been searching for gold. Miners began to arrive, though not many at first, because there was no surface water and the place was very far from anywhere.

In 1920 the opal field was given the name Coober Pedy. It comes from the Aboriginal phrase kupa piti, often translated as "white man in a hole" or "water hole." The town really grew from the late 1960s, when more people wanted opals and many migrants from Europe arrived.

Opal was discovered in February 1915 by members of the New Colorado Prospecting Syndicate, after 14 weeks of unsuccessful prospecting for gold; Britannica credits the find to Willie Hutchison, a boy in the party led by his father, James. Miners came sporadically at first because of the lack of surface water and the extreme isolation, but by 1920, after good rains, they numbered a few hundred. That year the local Progress and Miners Association named the field Coober Pedy, from the Aboriginal phrase kupa piti, which Britannica says is often translated as "water hole" or "white man in a hole."

The field has run in booms and busts. In late 1945 Tottie Kendall, an Aboriginal woman, and her partner Charlie Bryant made a major find at the 8 Mile field, which set off a new rush. Coober Pedy was designated a town in 1960 and grew rapidly in the 1960s and 1970s, with rising demand for opal, the arrival of many European migrants and the start of mechanized mining. A local council was established in 1987. The council's history noted in 2019 that over the previous 10 to 20 years, prospecting and the number of active miners had declined.

About 1,500 people live in Coober Pedy.

Their families come from many places. People speak lots of languages at home. Children go to school from preschool all the way to Year 12.

At the 2021 Census, the Australian Bureau of Statistics counted 1,566 people living in Coober Pedy. Of them, 236 were Aboriginal and/or Torres Strait Islander people. Many residents speak another language at home, such as Greek, Croatian, Serbian or Yankunytjatjara, an Aboriginal language.

The town's tourism association says more than 45 nationalities are represented. Many families came from southern and eastern Europe after the Second World War. Coober Pedy Area School teaches children from preschool to Year 12, and its students come from 49 different cultures.

The 2021 Census counted 1,566 people in the Coober Pedy locality, 57.1 percent of them male and 42.9 percent female, with a median age of 50 against 38 for Australia. Of these, 236 (15.1 percent) identified as Aboriginal and/or Torres Strait Islander. Only 58.1 percent used English alone at home, compared with 72.0 percent nationally; the top other languages were Sinhalese and Greek (4.5 percent each), Croatian, Serbian and Yankunytjatjara (1.3 percent). Local estimates run higher: the council's site gives approximately 2,000 people, and the tourism association cites a council estimate of about 2,500.

The tourism association reports more than 45 nationalities, with about 60 percent of people of European heritage, many descended from migrants from southern and eastern Europe after the Second World War. Coober Pedy Area School, from preschool to Year 12, says its students represent 49 cultures and that one-third of its enrollment is made up of Aboriginal students. The four main industries the association lists are opal mining, tourism, primary production and support services.

Coober Pedy gets very little rain, and it has no water source that lasts all year.

So water comes from deep under the ground. It is salty. A machine takes out the salt to make fresh water for the town.

There is very little rain at Coober Pedy and no natural water source that lasts all year. In 1922 the government built an underground tank to store water. Later, in 1967, a plant was built that used sunlight to turn salty underground water into fresh water, but it did not make enough.

Since 1985, the council has run a modern plant that removes salt from water pumped up from deep bores 23 kilometers away. Visitors can fill up at coin-operated water dispensers on Hutchison Street.

Low rainfall and no permanent natural water source shaped the town from the start. Its 1922 underground tank held 500,000 gallons, about 2 million liters. Because supply remained unreliable, the state government built a solar desalination plant in 1967, drawing salty water from 100 m below the surface; it produced too little and was often damaged by high winds.

Since 1985, the tourism association says, the district council has operated a reverse-osmosis desalination plant. Raw water is pumped from 60 m deep artesian bores 23 km northeast of town through a 200 mm pipeline beside the Oodnadatta Road, and the bore pumps are switched on and off automatically by radio signals from the treatment plant. Travelers can buy water from coin-operated dispensers on Hutchison Street.