A bystander has saved a dog from drowning after it got into deep water during a confrontation with a kangaroo.

Jono Lonie was at Pine River in Brisbane on Monday when a stranger's dog, likely a small terrier, started "just going off at the kangaroo".

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Lonie said that, with the owner nowhere to be seen, the dog wouldn't stop barking at the "massive" kangaroo, which he estimated to be about 1.5 metres tall.

"The kangaroo tried to run away and the dog continued to chase it," he told 7NEWS.com.au.

"It chased it into the water.

"The kangaroo started swimming across the river and the dog was behind it."

Tide turns

That's when the situation turned for the dog.

"The kangaroo turned around and started drowning the dog," Lonie said.

Play Video A small dog and a kangaroo have found themselves in an intense standoff that moved into the Pine River. A small dog and a kangaroo have found themselves in an intense standoff that moved into the Pine River.

"It went under a good four or five times.

"I just put the boat back in the water and went and got the dog.

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"If I wasn't there, that dog was dead."

Lonie said the kangaroo made it to shore and hopped away.

Lonie later found out the dog's owner was in mangroves looking for his pet.

A friend of Lonie's filmed the rescue as Lonie sprang into action with his boat to try to retrieve the dog.