Bindi and Robert Irwin Post Touching Tributes to Late Dad on Steve Irwin Day: 'I Still Look Up to Him'

Bindi Irwin/Instagram

Fifteen years after his death, Bindi and Robert Irwin continue to honor their late father's legacy by celebrating Steve Irwin Day.

On Sunday, the brother-and-sister duo each posted touching Instagram tributes to their late dad to mark the international event on Nov. 15, commemorating the adored Animal Planet star.

"Today is #SteveIrwinDay. Thinking a lot about my Dad today and the impact that he made on our planet, inspiring an entire generation," Robert, 17, wrote on Instagram with a throwback photo of himself, dad Steve and Bindi.

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"I also think about what a truly amazing dad he was," the wildlife photographer continued. "Through a lifetime captured on camera and stories from my family and those who knew him best, I'm able to remember the special times with dad."

"I still look up to him every day and while I miss him so much, it means the world to me and my family that each year we can have a day for the world to celebrate what he stood for," Robert added.

Bindi, 23, also acknowledged the special day with her own heartfelt post.

"Your legacy will live on forever. I love you for even longer. November 15, Steve Irwin Day," the mom to 7-month-old Grace Warrior captioned a smiling shot of her and her dad by the ocean.

RELATED: Bindi Irwin Calls Father Steve Irwin Her Daughter Grace's 'Guardian Angel' 15 Years After His Death

On Sept. 4, 2006, the beloved wildlife expert was working on the documentary series Ocean's Deadliest when he was attacked by a stingray off the coast of northern Australia and died at the age of 44.

In 2019, Bindi told PEOPLE, "Dad was my hero and the greatest Wildlife Warrior. It's a blessing to continue his work with my amazing family. We hope to make him proud every day. We are celebrating with lots of khaki and animals! Khaki's not just a color, it's an attitude!"

Robert added at the time, "Steve Irwin Day is one of the most special days of the year for our family. Dad was the ultimate Wildlife Warrior and so ahead of his time — discussing climate change, habitat destruction and so many other environmental issues before they were as widely discussed as they are now."

"He changed the world and so many lives across the globe," he continued. "For my family and me, we miss him every day, but are proud to keep his mission alive. It's wonderful to see so many people showing their support for his legacy."