Five snorkellers stranded on a tiny island off the east coast of Australia have been rescued after scrawling a giant SOS message into a nearby sandbank.

The group had been stuck out at sea for more than nine hours after their boat’s anchor failed and it drifted away.

They had been swimming around a remote sandbar near Wigton Island, Queensland, when the vessel started shifting - with their mobile phones, clothes, water and sunscreen all still on board – and it had moved beyond reach before they had time to react.

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Speaking to the Courier-Mail about the ordeal yesterday, Lyn Forbes-Smith described how she, a female friend and three male friends were facing the prospect of a long, cold night surrounded by ocean when they finally spotted an approaching rescue helicopter.

“We had sort of made plans about what we’d do on the rock for the evening,” she said.

“We had reef walkers on thankfully, but we had no food, water, cream, no hats, not much at all. We just looked for the highest ground, we looked for rocks where five of us could huddle together because we didn’t really want to separate, and we wanted to be out of the wind as best as possible.”

Ms Forbes-Smith explained that they were concerned the sandbar – and their message – would go under with the tide, but that they were “reasonably confident” someone would come looking when friends realised they had not returned.

The group had set off from Keswick Island towards Wigton Island at around 8am for the snorkelling trip, and it was around 5pm when they first saw signs of help approaching.

Another member of the group, Craig Gilbert, told ABC News of their joy at spotting an RACQ rescue helicopter.

“We saw the helicopter and we thought, 'Oh, you beauty' - and then it disappeared and we thought, 'Oh no - we better look out for our beds for the night' - then it came back probably 20 minutes later,” he said.

Rescue helicopter crew member Damien Kross said the five were treated for sunburn and dehydration, but were otherwise “fine”.

“They were a little bit dehydrated but we winched them to safety and brought them back here [to Mackay on the mainland] for just to have a quick medical attention and they were all fine.”