Sarah Robert-Tissot always says her engagement ring isn't lost, it's just out of reach.

"I know exactly where it is, I just can't get to it right now," she says, nonchalantly.

The ring is in a cabin in the Southern Quest — a 139-foot refitted trawler.

But unfortunately for Ms Robert-Tissot, the ship has been beneath the icy waters of the Ross Sea off Antarctica for more than three decades.

"The honeymoon suite was the first bit of the ship that sank because it went down backwards," she recalls of the night she abandoned ship in sub-zero temperatures.

"It was like 'oh my goodness, there's my room, sinking'. That was the last we saw of it."

In the footsteps of Robert Scott

Ms Robert-Tissot, who is formerly of the UK and now lives in Tasmania, was among a crew of more than a dozen people who sailed to Antarctica on the Southern Quest in late 1985.

She was a part of an expedition led by Robert Swan, a British adventurer who planned to recreate Robert Falcon Scott's 1911 walk to the South Pole — a 1,400-kilometre journey through ice and snow.

She and her husband Andrew joined the expedition on a delayed honeymoon — albeit one that wasn't very romantic, as she spent most of her time cooking in the galley.

The red-hulled Southern Quest was primarily used as a support vessel, ferrying a small plane to retrieve Mr Swan and his two companions from the South Pole.

Mr Swan only intended to walk the first part of the original expedition, as he wanted to avoid the fate of Scott's party of five, who perished on the return journey.

But unbeknownst to the crew on board the Southern Quest, they were edging closer to paralleling the fortunes of the former pioneers.

'You can't think about it, you can't collapse'

Sarah Robert-Tissot's engagement ring is still in her cabin at the bottom of the ocean. ( Supplied: John Elder )

The trawler, commanded by ex-British Antarctic Survey Captain Graham Phippen, left from Sydney. It anchored off Macquarie Island for New Year's Eve, then continued south.

On the night of January 10, 1986, Ms Robert-Tissot was disturbed in the middle of the night by the sound of constant banging.

Then, she heard a knock at the door. It was one of the crew.

"He calmly says: 'I'm sorry to disturb you but it's an all-hands situation'," she recalls.

While she had been sleeping, an ice floe — a vast sheet of thick floating ice — had swung into the path of the Southern Quest, pinning the ship. The banging noise had been the captain seeking a weak point in the ice floe.

The crew tried techniques similar to the ones former explorer Earnest Shackleton had used in 1915 to try and free his ship, Endurance.

Poles were thrust down from the deck to smash the ice from the hull and people used pickaxes and shovels to dig out the hull. They even loaded weights into cargo nets and swung them from side to side off the cargo boom to rock the ship.

But as they worked, the weather deteriorated; snow flurries filled the air and the temperature fell to -5 degrees Celsius.

Ms Robert-Tissot recalls the steel deck crumpling before her eyes "like a coke can".

"There was no time for someone to break into hysterical tears and require a good slap. That wasn't the theatre for it, really, it's a crisis," she says.

"There comes a time when you've just got to act, you can't think about it, you can't collapse."

But the crew remained on board waiting for the next order.

A second report came in — the ship was sinking. First mate David Iggulden recalls:

"The steel frames of the ship finally snapped with the pressure and as it snapped it tore the hull plating in and the water just gushed in … it was like watching the Titanic movie, the water just pouring in."

27 critical minutes

First mate David Iggulden recalls 'the first thing that went wrong' on the Southern Quest. ( ABC RN: Sophie Kesteven )

From the moment Captain Phippen gave the order to "prepare to abandon ship", they had 27 minutes to get everything they needed off the vessel.

"There was that moment of really wanting to panic," Ms Robert-Tissot says.

"You're going to make this leap of faith to step off the ship onto an ice floe [and] the thought of being in one of those life rafts, bobbing around in the Southern Ocean, in Antarctica, when I knew that I'd only just got dressed quickly; it would have been a nightmare."

Survival gear, radio equipment, food and medical supplies was thrown onto the thick ice. Mr Iggulden then contacted the nearby Polar Star and sent a securite message to the South Pole base.

"And they said 'hang on, your walkers have just arrived at the South Pole!' And of course, the walkers arrived to be told, 'oh by the way, your ship is sinking," he added, tongue-in-cheek.

The Southern Quest sank in less than 30 minutes. ( Supplied: John Elder )

The trawler sank at 11 minutes past midnight.

Everyone gathered on the ice, keeping back from the edge as their ship started sinking.

Sarah Robert-Tissot says the steel deck of the ship buckled like a can of soft drink. ( Supplied: Jack Robert-Tissot )

Ms Robert-Tissot remembers it was fast, going under less than 30 seconds.

"The action of the ship going down somehow pushed the ice floe away, and as the ship went in, a school of whales came up to look around and looked around as if to say 'what the hell is going on here?'" Mr Iggulden says.

"Then some penguins came out of the water and jumped up onto the ice next to us and they looked at us as if they saying 'who are you?' And that was quite funny."

The crew were well-equipped to trek the 48 kilometres inland to their expedition base, however, when the coastguard offered to send two helicopters to fly them to McMurdo Base, the captain accepted.

A helipad was created on the ice and they made a large "H" out of orange life jackets. When they heard the helicopters approaching, they set off orange flares so the pilots could see the direction of the wind.

From McMurdo Base, the crew was reunited with Mr Swan and evacuated to New Zealand.

Interestingly enough, bad weather and heavy ice interfered with both Scott's 1911 walk and Shackleton's 1915 expedition. It also played a part in the sinking of the Southern Quest.

Captain Phippen was cleared of any fault by a court of inquiry, and Mr Swan, determined to leave no trace on the icy continent, returned in 1987 to pick up the plane that he and his team left in the South Pole when they were evacuated by the Americans to New Zealand.

The Southern Quest, however, remains where she sank, with Ms Robert-Tissot's ring is still in the honeymoon suite, about six kilometres from Beaufort Island, in the Ross Sea.

