Mount Isa's World War II underground hospital, air raid shelter celebrates 80-year anniversary

The underground hospital consisted of male, female, and children's wards. (Supplied: Underground Hospital and Museum)

On February 19, 1942, at least 242 Japanese aircraft attacked Darwin, inflicting significant losses on naval bases strategically important to World War II efforts.

The attacks were the first of many air raids carried out by Japanese forces in the Northern Territory and parts of northern Western Australia.

Faced with threat of an inland invasion, it was feared north-west Queensland, in particular Mount Isa, would be targeted for its rich mineral resources.

Residents were concerned what would happen should the region's main hospital be bombed.

So locals banded together to create a tunnel network that would become Australia's only underground hospital.

Nurses, including Eileen Richardson, used the hospital to sleep in after night duty as it was cool and quiet. (Supplied: Underground Hospital and Museum)

Miners worked long hours to drill and blast a series of four timbered tunnels into the side of a hill while nursing staff kitted out the facility with equipment for an operating theatre, delivery room and wards.

While the war never reached the region and the hospital was never used, it has become a symbol of communities pulling together during times of great crisis and chaos.

A mock operating set-up in 1942 to show how an operation would be carried out inside the hospital. Nurse Eileen Richardson is on the operating table. (Supplied: Underground Hospital and Museum)

Volunteers preserve site 

After sitting idle for almost 50 years, locals decided the site needed to be preserved and that its history should be shared with a wider audience. 

It opened as a tourist attraction in 2001.

Locals and tourists gathered at the Underground Hospital on Sunday to celebrate the attraction's prominent history.  (ABC North West Queensland: Emily Dobson )

The Underground Hospital operates with an 18-strong volunteer workforce, drawing 7,500 visitors per tourist season for guided tours. 

Locals and tourists gathered at the site on Sunday to commemorate its 80th anniversary. 

Despite its longevity, the hospital was still awe-inspiring for visitors.

"It's just so fascinating that in 1942 they had to go to the extent of building an underground facility in case the invasion happened," tourist Harold Patullo said.

Harold Patullo and Gertie Taylor decided to return to the Underground Hospital for a second visit.  (ABC North West Queensland)

Mr Patullo was visiting the Underground Hospital for the second time, travelling from Victoria. 

Volunteers guide 7,500 people through the attraction each tourist season.  (ABC North West Queensland: Emily Dobson )

Tourist Cheryl Wallace said it highlighted an important part of Australian history.

"It was a long time before the whole Australian public realised how much of a threat Australia was under with the bombing of Darwin, we really didn't know much about it," Ms Wallace said. 

"What they've done is incredibly valuable to understand how threatened they felt during the war."