OLYMPIC champ Greg Lou­ganis is making waves with his new celebrity “Splash” series, but he has an ocean of sordid secrets in his past – involving rape, multiple sui­cide attempts and hard drug use.

The 53-year-old Olympic sports leg­end, who’s a trainer and coach on the ABC celebrity div­ing competition, says he grew up beaten and abused by his alcoholic stepfather, leaving terrible emotional scars.

“I was a miserable kid,” Louganis reveals in his autobi­ography “Breaking the Surface.” “At 12 years old, I decided I would kill myself.”

GREG SWALLOWED SOME PILLS and dragged a razor across his wrists, but did not cause fatal damage.

Suffering from severe mood swings, he started smoking marijuana in seventh grade and later graduated to cocaine.

“Depression has been a major problem all my life,” he divulged in his 1995 tell-all.

As a young man, Greg was also coming to terms with being gay.

“I started to think that I should just leave, kill myself, commit suicide,” disclosed the athlete, who wrote a suicide note, swallowed a handful of Valium and codeine, “got into bed, and prayed I wouldn’t wake up.”

He tried to commit suicide a third time, by taking Quaaludes and speed.

In 1982, a boy­friend got enraged after learning Greg was seeing other men.

As punishment, Louganis says the man held a “knife at my throat, tore off my clothes…

“Then he raped me!”

Now living with HIV for nearly 25 years, Louganis, who found help in rehab, is amazed he’s still alive, says a pal.

“He’s managed to bounce back stronger than ever.”