A heartfelt letter from world-renowned conservationist Steve Irwin has been discovered nearly 10 years after his death.

Irwin's father, Bob Irwin, discovered the note earlier this year while researching his memoir, news.com.au reported.

The letter, addressed to both of Steve Irwin's parents, reads:

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

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!

On the envelope Steve Irwin wrote, "Please be happy to know that your strength and wisdom have been passed on."

Bob Irwin's memoir, "The Last Crocodile Hunter: A Father and Son Legacy," is scheduled to be released in October. It will include Steve Irwin's letter.

Sunday marks 10 years since Irwin's death.