A couple is lucky to be alive after they became stranded in the remote Australian outback with no food or water for two days.

Jose Merlos, 29, and his fiancee Nicky Wong, 32, walked more than 40km in the blazing heat to seek help after their car got bogged in the sand on January 3.

The pair, from Findon, were on holiday in Cairns when the South Australian government introduced a hard border closure with NSW in response to the latest virus outbreak in Sydney.

In a bid to get home without driving through NSW, the couple drove inland from Cairns before taking rural backroads through northern SA.

But they found themselves in some serious trouble after their car became bogged in the sand.

They abandoned the vehicle, leaving a note saying they would walk to Innamincka – a small town near the South Australian border with Queensland.

They had no phone reception and were relying on a preloaded map, the Adelaide Advertiser reported.

The couple told the Royal Flying Doctor Service (RFDS) they walked for more than 40km in scorching heat with their dalmatian pup Loki.

A picture supplied by the RFDS shows the couple had even resorted to scrawling SOS in the sand while leaving several notes along the route, urging passers-by to call emergency services.

But they got lost, and feared time may be running out.

“It was so hot and we were scared, I thought we were going to die,” Mr Merlos said, in a statement to RFDS.

“My phone said SOS only, and I kept trying over and over again to call for help but the call wouldn’t go through.”

They resorted to drinking muddy water from a cattle trough and even their own urine, which Mr Merlos said he couldn’t stomach.

“We had no more water left, so I saved my urine in the bottle, like in the movies, you think just in case of emergency,” Mr Merlos told the Adelaide Advertiser.

“That’s when I thought we were done for. Because (we had) no more energy to walk, we were thirsty, very thirsty, dreaming of water, and dreaming of a beer.”

Then, after another day in sweltering heat, they spotted a car approaching the pair.

Driving the car was Craig, a Santos worker who said he only took that route every six weeks. He had seen their notes, pleading for help.

“Craig told us he only took that road once every six weeks, and we had another 25km to walk to get to Innamincka. If he hadn’t found us, we would have perished,” Mr Merlos said.

Craig took them to town where they were given food and water and treated by the RFDS. After two days in recovery, the pair headed back to Adelaide.

RFDSSE nurse practitioner Chris Belshaw, who treated the pair, said they are lucky to be alive.

“Luckily for them, the temperature was lower than usual for this time of year, and only in the mid to high 30s … usually it is 45 at this time of year,” he said.

“If it was the normal temperature then I believe they would have perished.”

Loki the dalmatian was unharmed.