Pictures released by paramedics show the woman's bare feet between the rocks in Hunter Valley, north of Sydney, Australia.

She had been stuck for an hour when her friends, who had tried to free her themselves, called the emergency services to move the 500kg boulder.

Specialist rescue paramedic Peter Watts, from New South Wales Ambulance, said: "In my 10 years as a rescue paramedic I had never encountered a job quite like this, it was challenging but incredibly rewarding."

Mr Watts worked with other agencies to remove several boulders and reach the woman's feet.

The team then assembled a "hardwood frame" to ensure no rocks gave way while rescuers delved gradually towards the three-metre gap, according to NSW Ambulance.

It took six hours for the rescuers to clear the site and free the woman, with an hour needed just to navigate the woman out of the tight "S-bend" gap.

"Every agency had a role, and we all worked incredibly well together to achieve a good outcome for the patient," Mr Watts added.

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The woman resurfaced with only minor scratches and bruises.

Her mobile phone, however, remains at the bottom of the crevice.

The ambulance service did not say exactly when the incident happened but said it was earlier this month.