It is over 20 years since diving gold medalist Greg Louganis first spoke publicly about his homosexuality and positive test of HIV.

In those two decades, Louganis has been an activist for LGBT, an activist for fighting HIV/AIDS, a writer, an actor, and a coach.

The journey from being raised by adoptive parents to diving prodigy to the present day has lasted even longer. In the documentary "Back on Board," HBO cannonballs into the twists and turns of Louganis' life.

Here is a sneak peak at the film with Louganis discussing his 1976 relationship with rival Soviet divers:

"Back on Board" debuts tonight (Aug. 4) at 10 p.m. ET/PT.

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