Their bodies were discovered on Thursday in the submerged vehicle during a search for two missing tourists from China who disappeared in flood-ravaged Queensland.
The tragedy marked the first flood-related deaths in the rain-drenched region as other communities braced for rising river levels.
The backpackers - a 26-year-old man and 23-year-old woman - left Brisbane on Sunday to take the four-hour drive up to the North Burnett region.
"Their intention was to go to Mundubbera to do fruit picking," Police Minister Dan Purdie told reporters on Thursday.
A friend reported them missing on Tuesday, sparking a large-scale search.
But it was a member of the media who discovered the submerged car the next day at Kilkivan, west of Gympie.
"It looks like the vehicle has driven off a bridge into flooded waters, which is really sad to see," Mr Purdie said
Police divers located the bodies in the vehicle on Thursday morning.
"The formal identification process is still under way but it is believed that the two ... are a 26-year-old male and a 23-year-old female who are international tourists," Mr Purdie said.
The victims' families have been notified and will travel to Australia as police work with the Chinese consulate.
"I appreciate this is a horrible time for their friends and family and loved ones and our heart goes out to them," Mr Purdie said.
The deaths devastated the Gympie Shire where the bodies were found, in another blow to a community reeling from wild weather.Â
The region near where the vehicle was discovered had been one of the hardest hit, Gympie mayor Glen Hartwig told AAP.
Up to 400mm of rain fell in 24 hours before floodwaters "absolutely smashed" the region's western areas.
Crops, fences and roads were destroyed but the full extent of the damage won't be known until floodwaters recede.
"Looking at the financial impact on farmers, it will be 12 months before they will take any money from these paddocks that have been destroyed," Mr Hartwig said.
Chinchilla, northwest of Brisbane, had been next in line after Bundaberg was flooded on Wednesday, swamping hundreds of houses and businesses.
An emergency was declared and exclusion zone set up in the Western Downs town as locals evacuated to the showgrounds.
Nearby Charleys Creek peaked on Thursday at 6.4m, well short of the 2011 record of 7.45m, but more than 60 homes and businesses were still impacted.
Attention has turned further west to Longreach where residents face an anxious wait ahead of the town's first major flood since 2000.
Extra emergency services have been deployed to the outback hub to combat the Thomson River which is set to peak on Saturday.
Door knocking is under way to evacuate vulnerable locals including aged care and nursing home residents.
"We've got about 25 dwellings and buildings where water could go into the lower lying areas of town," Longreach mayor Tony Rayner said.
In the Northern Territory, multiple flood warnings and watches are in place across the saturated Top End.
Residents have been evacuated at Katherine, with further river rises expected.
A boil water alert has been lifted at Darwin after flash flooding but it remains at Katherine and Jilkminggan.
A mother and her children were rescued from a roof when flash flooding hit south of the NT capital on Monday, swamping about 20 homes.
The federal and NT governments on Thursday announced extended assistance to flood-hit communities.
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