The population of LIGHTNING RIDGE , 74km north of Walgett on the Castlereagh Highway (the road is fully sealed, but note that there's no place to stop for fuel between the two), is officially 4000 but unofficially it's reckoned to be about 10,000. It's a transient place, where people in their hordes pitch up in town lured by the town's one attraction: opal. Amid this harsh landscape scarred by holes and slag heaps, Lightning Ridge's opal fields are the only place in the world where the extremely valuable black opal can consistently be found. This lone enticement is heavily exploited by opal galleries and mines you can visit, among them the Big Opal, 3 Mile Rd (daily 9am-5pm; tours 10am & 2pm, $11), which has demonstrations of opal-cutting and guided tours of an underground mine; Spectrum Opal Mines, Bald Hill Road (daily 9am-5pm; $3), a centre displaying solid opals in an underground showroom with a film about opal-mining shown on the hour; and the Walk-in Mine, 1 Bald Hill Rd (daily 9am-4pm; tours $6), which has a mining display and tours to an underground mine. There's even an opal and gem festival in late July, which sees the population shoot up by another few thousand souls. The effects of the opal obsession can be seen all over town, in the faces of the residents and the glorious, crazy constructions of the few who do strike it rich; check out the Bottle House at 60 Opal St, a bizarrely beautiful cottage and matching dog kennel built entirely from wine bottles set in stone.

There are clearly demarcated fossicking areas where you can try your luck at finding opals - but don't do it anywhere else, or you may stray onto others' claims. Recover afterwards in the 52°C water of the Hot Artesian Bore Baths on Pandora Street (open 24hr; free). More cooling is the Olympic Pool on Gem Street (end Sept to Easter daily 10am-8pm), particularly appealing in the scorching heat since parts of the pool are shaded from the sun. The Goondee Aboriginal Keeping Place on Pandora Street (call tel 02/6829 2001 for opening times) has Aboriginal artefacts and information on bush tucker.