It piqued Yvette Poshoglian's curiosity on her regular kayaking trips and eventually prompted her to spend two years researching the institution's brutal history for her book Escape From Cockatoo Island, published this month.

''I had known a little of the prisoner island history of Cockatoo and that it had a naval history, but I never knew that it housed an institution for destitute and wayward girls,'' she said.

Part of the My Australian Story series of historical novels for older children, Poshoglian's book is the fictional diary of an 11-year-old orphan, Olivia Markham, who has been sent to Cockatoo Island because she has no parents.

Olivia soon discovers that conditions for the 88 inmates at Biloela are scarcely better than they were for convicts as they are forced to work in sweatshop conditions and suffer harsh, arbitrary punishments.

A high school English teacher, Poshoglian scoured libraries, the NSW government's archives in western Sydney and read the diaries of the superintendent of Biloela as part of her research.

She also wrote part of the book on Cockatoo Island in the rooms where girls like the fictional Olivia would have lived.

''I was quite spooked by the experience,'' she said.

''The wind howls through the walls and the isolated nature of the place hits you with every breath you take.''

Poshoglian said Biloela was established in 1871 to deal with ''street arabs'', a term used to describe orphans and homeless children.

''Sydney wanted to be rid of this problem and so they lumped the children too young to be sent to jail to a variety of institutions,'' she said.

''Biloela was both a reformatory for young criminal females and an industrial school for the orphaned and destitute.''

Boys of the same age were housed and taught tailoring, sail making, carpentry and nautical skills on the Vernon, a ship moored off Cockatoo Island.

The chief heritage architect at the Sydney Harbour Federation Trust, Libby Bennett, said Biloela was one of many ''layers of history'' preserved on the island, beginning with Aboriginal people who used it as a base for fishing.

She said Cockatoo Island was used to house convicts and then orphaned and criminal children because it was difficult to escape from.

Biloela's poor reputation eventually prompted an investigation by the Herald, and the establishment of foster care in NSW.

''When authorities investigated, they were horrified by what they found,'' Poshoglian said.

''Abuse, poor health and squalor were the order of the day. Surely many had gone mad.''

Poshoglian said Biloela was also an experiment in what was called ''petticoat government'' after the institution was handed over to an entirely female staff.

More than 130 years later, Poshoglian said the abuse of children in institutions remains an issue: ''There is also something to be said about locking up children on islands and leaving them for indefinite periods of time without access to schooling and society.''