Jackson Vincent snapped these astounding photographs of the huge roo tensing its rippling muscles in Boodjidup Creek in Margaret River, Western Australia.
He said: “I have been going to that creek since I was a little boy and there have always been kangaroos on the property.
“I was walking my dog and we saw this huge roo standing in the water. I have never seen a kangaroo standing in the water like that, we could just see his head at first.
“As I ran around him to take a picture he came closer and that was when I realized he was coming right at me and he was really big – one of the biggest I have ever seen.
“I am pretty confident around animals but the moment when he started to come out of the water my heart definitely jumped and I decided to take a few steps back.
“He looked to be at least two meters tall or taller and must have weighed at least 100 [kilograms].
“He had a really big body and was taller than me. There are a lot of roos at my grandma’s place but I have never seen one that muscular before – he was a big macho male.
“I decided to get Dharma out of there as we thought the kangaroo was going to lure her into the water to drown her.”
Jackson added: “His claws were really big – they were as long as my hand. That for me was even scarier than his muscles, they looked nasty.
“I have never seen a kangaroo be so defensive – it definitely looked like he was puffing his chest muscles up.
“I definitely wouldn’t like to take him on in a boxing match.”
But the animal may not have just been cooling off, as kangaroos are known to jump into the water to escape predators.
“If they see a dog, and they think that’s a potential predator, they’ll get into the water in the hope that the dog won’t pursue them,” wildlife biologist Bill Bateman told the ABC.