Terri Irwin has revealed the promise she made to her late husband Steve Irwin before his tragic death.

She opened up about the crocodile hunter's dying wish in a new documentary called Crikey! It's the Irwins: Life in Lockdown.

She explained that she promised Steve that she would continue to run the zoo he established on the Sunshine Coast and it would continue operate.

"He said to me, if anything happens to me, just make sure Australia Zoo continues. So it is really important that we keep this going," Terri explained in the emotional clip, which you can watch in the player above.

Australia Zoo has faced financial hardship due to the loss of the tourism dollar as well as Australia closing its borders to international travellers.

Terri informs Bindi, 21, and Robert, 16 that she was unsure how long the zoo would need to be closed due to the coronavirus pandemic.

"We don't really know how long we're going to be shut down for," Terri said.

"It might be another month, it might be another six months."

In the video, Bindi said that she wishes her father was still around to help out the family during the tough time.

"I just keep thinking gosh, I just wish dad was here to help us out with everything, you know," Bindi said.

"We have enough food to continue on for about six weeks," Bindi explained about the zoo, adding, "But after that we are going to seriously be running out of funds."

Terri said that the family have been brought closer together after the death of Steve, who passed away after being stabbed in the chest by a stingray on the Great Barrier Reef.

"We communicate well, and I think it's a natural effect of losing Steve. I think we became closer and stronger as a family and we have developed this awareness that allows us to truly value the people closest to us even more than we already did," Terri told The Australian Women's Weekly in 2019.

"It's sad that it takes a tragedy such as Steve's death to amp that up in your life, but it does make you want to live every day to the fullest and appreciate the people you love," she added.