Terri, 52, took to Twitter on Sunday to share a photo of the couple kissing while an iguana sits on their heads.
“Today would have been our 25th wedding anniversary,” she captioned the black and white image. “I miss you so very much, and I am grateful every day for the time we had together.”
Steve was working on a documentary series titled Ocean’s Deadliest when he was stung by a stingray off the coast of northern Australia and died on Sept. 4, 2006 at the age of 44.
He and Terri shared two children, Bindi, 18, and Robert, 13. Both Bindi and Robert have continued to follow in their father’s footsteps, regularly working on behalf of The Steve Irwin Wildlife Reserve and the Australia Zoo.
Robert appeared on The Tonight Show Starring Jimmy Fallon on Thursday, where he spoke about his work with the Australia Zoo.
Bindi praised her brother’s appearance on the show by sharing a heartfelt message on Instagram.
“I’m beyond proud of you tonight Robert! You are such an extraordinary human being and inspire us all. Love you so much!” Bindi wrote.
In August of last year, Terri revealed that she hasn’t been on “a single date” since Steve passed.
“I haven’t been on a single date since Steve died,” she told The Australian Woman’s Weekly.
“If I hadn’t met Steve, I probably would never have married because I wasn’t looking for love when I met him,” she said of her relationship with Steve. “What we had was incredible.”
Last month, Bindi opened up about her mother’s long-lasting love for her father to E! News
“My dad is still very much my mom’s soul mate. And I think that no matter what, Mom always says that they’ll always be married,” Bindi said in the interview. “And to her, mom and dad, they’re always going to be together. So in this life and the next, they’re a couple and a team. So I think that’s really important.”