Universal Studios Hollywood WaterWorld Performer Needs CPR, Rushed to Hospital

A "WaterWorld" performer at Universal Studios Hollywood is hospitalized after taking a 30-foot drop into a tank, and not coming back up for air ... TMZ has learned.

Authorities tell TMZ ... the incident happened during a Monday show at the theme park. We're told the performer went into the water -- as planned in the show, but it was clear something went wrong when he did not immediately surface.

We don't know if the performer had a medical emergency while underwater, or if he was somehow injured by the 30-foot fall into the tank ... possibly getting knocked out on impact.

When folks noticed the performer wasn't coming out of the water, we're told employees pulled him out and he was given CPR on the spot for more than 5 minutes.

Those employees were able to get his heart beating again, and the performer was then rushed to a hospital. It's unclear what his condition is currently.

A spokesperson for Universal Studios Hollywood confirms the performer is still being treated at the hospital.