THE father of late “Crocodile Hunter” Steve Irwin says his son’s public geniality masked an inner turmoil.

“People don’t realize just how much he gave of himself,” Bob Irwin told Australian TV.

“He was always very good in front of the media, and a lot of the pain and the suffering didn’t show,” he said, without elaborating.

Steve Irwin was 44 when he was killed in September 2006 after being struck in the chest by a stingray barb.

Irwin had shot to fame as the gregarious, enthusiastic host of Animal Planet’s “The Crocodile Hunter.”