In Mintabie, South Australia, The Tunnel Rats are under extra pressure as rival miners close in on their claim. In Sheepyards, NSW, The Bushmen must brave an abandoned mine to remove a dead animal. Meanwhile, rookie prospectors The Poms seek a prize opal to kickstart their mining career.

The Bushmen face off against a miner who has illegally dug on their claim.

The Tunnel Rats deal with an unexploded bomb and hazardous gases; The Bros attempt to fit their equipment into a new mine; The Poms make their first trip underground.

In Opalton, Boulder Boys Aaron and Ron's excavator has a close call.

The Bushmen take a big risk, trying out a new mining method deep below the ground, and injury slows down progress for The Bros and The Poms are struggling to find their first piece of opal.

The Boulder Boys, who are within reach of their $100,000 season target, chase old leads that could see them strike it rich and The Bushmen face a disaster underground.

A violent summer storm sees The Young Guns race to save their only claim from a flood; meanwhile The McFarlanes must build a drill from spare parts.

Tunnel Rats Bayden Pearse and Leese Grobe get the lifeline they desperately need. Meanwhile, Pete Cooke and Sam Westra are on the last dig of their season, and 20-year-old Sam must decide whether to quit opal mining for good.

The Australian outback's wildest treasure hunters face even bigger challenges in their quest to strike it rich, as they seek the legendary queen of gems: the opal.

Following six teams across Australia as they search for the country's most iconic gemstone.