Grant Hackett has contacted his family to tell them he is safe, after they issued a public plea for help to find him when he went missing this morning.

The Hackett family took to the media to raise their concerns for the welfare of the 36-year-old Olympic champion, after he checked out of a Gold Coast hotel this morning and vanished in what his father Nev Hackett described as a "disturbed" state of mind.

Mr Hackett said police had found his son after a member of the public called to tell them where he was.

"Police officers are happy he's alive and sober," Mr Hackett said.

"He's told the police officers he just wants to hide from everybody."

He said Grant sent his mother a text message to tell her he loved her, but could not talk any further.

"He's in hiding from everybody, including us," Mr Hackett said.

"I think he's very, very embarrassed, but let's see how things go."

He said things had been "pretty tough" for the family today.

"I say we were ready for the worst, so yeah pretty tough," he said.

"I'd hate it to get any worse because my wife's a wreck, as expected."

Mr Hackett thanked the media for helping to locate his son.

The swimmer was arrested yesterday after an altercation at his parents' house in the Gold Coast suburb of Mermaid Waters.

He was later released without charge.

But by this morning he could not be found.

"We're extremely worried about him," Mr Hackett said earlier.

Sorry, this video has expired Nev Hackett issues a public plea for help to find his son

"His doctor can't find him, he hasn't kept an appointment with his lawyer. When we spoke to him several hours ago he just hung up when we asked him where he was.

"His mates are out there looking for him but we need more help."

Grant's brother, Craig Hackett, said on Wednesday his brother was "a danger to himself".

'People need to give him space and time to heal'

Libby Trickett said her former teammate needed time and space to heal. ( ABC News: Mel Vujkovic )

Former Australian teammate Libby Trickett also expressed concern for Hackett's welfare, saying the transition to life after swimming could be incredibly difficult.

"He's obviously vulnerable right now," she said.

"I hope he's just somewhere safe with other friends and family, that might be protecting him right now and giving him space outside the public eye.

"I think people just need to give him a lot of space and a lot of time to heal, because this is a mental health issue."