In the image, Rob is reaching out his hand to a large manta ray. It's safe to say that the poignant image reminded many people of how the teenager's dad lost his life.
"I did not realise I had ptsd until this moment. Please be careful," one user commented.
"You stay the f**k away from them rays alright" another added.
"We all thought the same thing! Just shows how much of a impact it all had on us! Definitely the photo of the century," another added.
While many of Rob's followers were alarmed at the picture, there were others in the comments who quelled any anxieties about the 17-year-old's underwater expedition.
"That manta ray looks absolutely gorgeous! And for everyone in the comments manta rays don’t have barbs," wrote one user.
Steve Irwin lost his life on September 4th 2006 while filming in the Great Barrier Reef. The Crocodile Hunter was tragically struck in the chest by a stingray barb.
Years following his death, in 2018, Bindi Irwin revealed her true feelings about stingrays.
WATCH: Bindi Irwin Reveals Her True Feelings About Stingrays (Story continues after video)
When asked whether she felt any bitterness toward rays, Bindi told the late US talk show host Larry King that she doesn't.
"It was just a crazy accident that happened," the now-22-year-old said.
“Stingrays are really beautiful animals. Dad loved them, we love them and they are important to our environment. And I know dad would be the first person to say ‘I love stingrays.’”