Woman, 21, dead after Sydney lookout fall

A 21-year-old woman has died after falling and suffering a serious head injury while on a morning walk with a friend at North Head Sanctuary on Sydney's northern beaches.

The woman fell about 5.30am on Wednesday and died at the scene, while her 21-year-old friend has been assessed by paramedics and taken to hospital with shock.

NSW Police Acting Inspector Stuart Byrnes said the circumstances leading to the woman's fall from the lookout, which is surrounded by "inhospitable" terrain, remained unclear.

"We are very light on details at the moment ... there's no need for a warning, we believe it was a very sad accident," Insp Byrnes told reporters on Wednesday.

"Our thoughts go out to the family."

Insp Byrnes said the case would now go to the NSW coroner.