Bindi Irwin's emotional Father's Day message for Steve

Steve Irwin and his children (Terri Irwin/Twitter)
Steve Irwin and his children (Terri Irwin/Twitter)

Bindi Irwin has published an emotional Father's Day message for Steve Irwin, on the 10th anniversary of his death.

"You'll be my hero for my entire existence. I love you more than words can describe," she said on Twitter, as she showed a picture of her father holding her as a baby.

The wildlife conservationist died after his heart was pierced by a stingray barb while filming a documentary.

His wife Terri also had a message for him, saying "Happy Father's Day Australia. Hug your dad."

His father Bob also had a message, as he published a previously undiscovered letter from Steve to his parents.

"Probably one of the most unfortunate things in a 'Bloke's Life' is that it takes over 30 years to realise how essential you have been to build my character, my ethics and, most importantly, my HAPPINESS (sic)," wrote Mr Irwin.

"At 32, I am finally starting to figure it out. In good times and in bad, you were there. Your strength and endurance to raise me will not go unrewarded. My love for you is my strength!

"For the rest of my life I will reflect on the unbelievably GREAT times we've shared and will continue to share. You're my best friends!"

Bindi previously posted a message on her 18th birthday in July.

"Our Dad, Mum's soulmate and a superhero for us all, passed away. However, since this photo was taken, 18 years ago, one life ingredient has remained, unchanged, unbreakable. That is the unconditional love that is shared between my beautiful little family and the loyalty we have to eachother and everyone else who has taken this journey with us (sic)," she posted.

"I don't think that when this photo was taken even my beautiful parents could have known what life would evolve. I know that I am endlessly grateful for the love and light I have been given since Day 1 of my life," she said.