A man who survived a suicide attempt off San Francisco's Golden Gate Bridge and was kept afloat by a sea lion has relayed his story to a NSW Police suicide prevention conference.

San Franciscan Kevin Hines, 33, was the keynote speaker at the NSW Police Force biennial conference on improving policing strategies in mental health related cases.

This year's theme was suicide prevention, intervention and postvention.

Mr Hines's story is one that he never expected to tell.

"I was suffering mentally with bipolar disorder, type one psychotic features ... and I was hearing voices ... that were telling me I was useless, worthless, not meant for this world and a burden to all who loved me — none of that was true but I couldn't see it," he said.

"I had fallen into such a depression, that I was in this bit of tunnel vision that led me to believe that I had to die.

"I never wanted to, when they became so apparent and so overwhelming that's when the thoughts of ending my life came into play and that's when I was on that bridge and the voices were literally screaming in my head, 'you must die — jump now'.

"And that's what I did."

Mr Hines says he remembers everything.

"[I was] in the water desperately trying to stay alive and stay afloat, [and] I guess you would call it a mammal began swimming beneath me and I'm thinking, 'Oh man, a shark is about to devour me'," he said.

Mr Hines later found out that was not the case.

"I was on a show for suicide prevention and I mentioned that I thought there was this shark on this show and a man wrote into the show and he said, 'Kevin, I'm so very glad you're alive, I was less than two feet away from you when you jumped'," he said.

"He said: 'It haunted me until this day; it was no shark, it was a sea lion and the people above looking down believed it to be keeping you afloat until the coast guard brought a ride behind you.'"

But Mr Hines said he would have died of hypothermia before the coast guard found him, if a driver by had not seen him jump.

"She called her friend in the coast guard, which is the only reason they arrived to my position within less than the time I [would have] set in hypothermia and drowned."

The last piece of the so-called three-part miracle, which Mr Hines attributes to God, was a doctor who was not supposed to be there.

"[The doctor] stayed for another reason. I came in, he performed a 14-hour surgery on my back giving me the ability to continue to be able to walk," Mr Hines said.

Hines tells of how he came to share his story

Mr Hines said he had no intention of ever talking about his experience, and that he was embarrassed and extremely sad.

"I got out of the hospital, went into a psych ward, got out of the psych ward," he said.

"I'm now in a back brace and a [using a] cane, at church with my father and the priest I'd known all my life comes out and says 'come and talk to our students on Good Friday'," he said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 44 seconds 4 m 44 s Kevin Hines shares his survival story Download 8.7 MB

"I talked to 120 kids and two weeks later I got 120 letters in return and the letters were amazing, I read every one.

"I didn't think I was going to make an impact, I didn't think I was going to help a soul.

"At that speech I shook and I cried and I barely got through it and these kids were impacted.

"Several of them were actively suicidal, because of that we were able to get them help and it became what it is today and that's just travelling all over the place and trying to help one person in an audience."

Mr Hines still lives with paranoia, auditory and visual hallucinations, manic highs and depressive lows from bipolar disorder and panic attacks.

"And that's OK — I'm alive," he said.

His message today is that for those with suicidal thoughts, there is another option.

"I think the message is very, very simple: you don't have to die this way. And that today is not tomorrow," he said.

If this story has raised concerns for you or someone you know, you can contact Lifeline 24 hours a day on 13 11 14.