As the clip (in the player above) went into slow-motion, Robert glanced up at someone off-camera and in that moment he looked so much like his dad that it almost felt like Steve Irwin was with us again.
Then the 18-year-old grinned before flipping backwards into the water, laughing as he clambered back up onto the wooden platform moments later.
Fans were blown away by the resemblance, one writing in the comments section: "Gosh you've got your dad's face mate."
"Mini Steve. We love you Robert," another said, while a third chimed in, "I see your dad in your face more and more."
There have always been similarities between Robert and his dad, who tragically died in 2006, just months before Robert's third birthday.
Though the now-teenager didn't get to spend much time with his dad before he passed, Robert has kept Steve's memory alive through his wildlife conservation work and role at Australia Zoo, where he and sister Bindi have helped fill their dad's shoes.
Robert shares many of his adventures and projects on Instagram, as well as family moments and fun clips like his latest backflip video – though the clip caught some unwanted attention too.
Many fans were distracted by Robert's physique, the usually covered-up Wildlife Warrior revealing broad shoulders and a six-pack in the footage of him by the water.
There were plenty of comments asking him to share his workout routine, though some crossed the line into inappropriate innuendo that left other Instagram users uncomfortable.
"He's 18 ffs [for f—k sake] cut it out with the thirsty comments and blatant objectifying. How would you feel if it was your kid?" one person wrote beneath a suggestive comment.
Many celebrities choose to keep their children off social media these days in a bid to avoid unwanted comments like these, though Robert and Bindi have had public profiles for years now.
This story originally appeared on our sister site, Now To Love.