Bystanders launched into action after seeing a woman holding an eight-year-old girl's head under water off Brisbane's bayside yelling: "We will be together forever".
They quickly alerted a nearby police officer who waded into Moreton Bay with a concerned local, finally convincing the distressed mother to return to shore with her scared daughter.
Asked to explain her actions, the woman told police: "I've just had enough, I want to end it all for us".
The 31-year-old woman had suffered from a severe mental illness complicated by drug use and a history of harmful alcohol abuse for years, the Supreme Court heard on Friday.
By May 2019 the woman was in the "throes of the illness" after drinking.
On a cold day, she took her daughter to a Manly beach and forced her into the water.
The reluctant girl was hit, yelled at and had mud smeared in her face before wading out when her mother grabbed her by the neck.
"Under the influence of your illness you treated her dreadfully," Justice Soraya Ryan told the woman on Friday.
The woman held her daughter's head under water before being coaxed back to shore, only to become irrational as emergency services tried to help.
It took four people to restrain the screaming woman who was sedated four times before being taken away by ambulance.
"You were obviously under the influence of paranoid delusions at the time," Justice Ryan said.
The woman spent a month in hospital before being taken into custody.
The daughter - currently in her aunt's care - made a full recovery, writing a "very compassionate" victim impact statement.
"She recognises you were not yourself when you tried to harm her. She knows how much you love her," Justice Ryan said.
"She sounds like a very special girl who has been through a lot.
"You offended against a person I am guessing you love more than anything else in the world and you have to live with what you did to her forever."
For years the woman had suffered symptoms including auditory hallucinations and persecutory delusions, with Justice Ryan describing them as "one of the worst I have seen".
Overall the woman spent almost 21 months in custody including mental health facility stints.
She was released on bail early last year with two electroconvulsive therapy sessions helping bring her illness "under control".
She is taking steps to be reunited with her daughter.
The woman on Friday also appeared on a dangerous driving offence after picking up her daughter from school despite being two times over the legal limit in March 2019.
She almost hit pedestrians, students and other vehicles with her car before crashing into a residence's fence.
For attempted murder, the woman was sentenced to five years in jail, wholly suspended for five years.
For dangerous driving, she received three years in prison but was immediately released on parole.
She had pleaded guilty to both charges.
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