George Clooney's children think he "plays in the water" for a living.

The 'Boys in the Boat' filmmaker has admitted his six-year-old twins Ella and Alexander - who he has with wife Amal Clooney - don't have the best grasp on what their famous dad does for work.

Speaking to Entertainment Tonight, he said: "They think that all I do is play in the water.

"I did a movie a couple years ago called 'Midnight Sky'. I had to shoot stuff in a tank and they came to visit.

"I'm like in, you know, clothes but I'm in a tank and they just assume that I swim. So whenever I say I go to work, they think I'm swimming."

The 62-year-old actor recently revealed he has a ploy to make sure his children are behaving by pretending to phone Santa Claus.

If they are acting up throughout the year, he enlists the help of a friend who poses as Father Christmas himself to remind them to behave again in the run up to the big day.

He told People: "They're still all into the Santa thing, which is very helpful, because when my kids are acting poorly, let's say in July, I have a call from Santa.

"And I go, ‘Hey Santa, how's it going?’ And he's like, ‘Everything's going good. How are the kids?’ And I go, ‘Well, I don't know. Kids, how are you guys doing?’

"They're like, [whining]. And then I get away with it. I actually have a buddy whose phone comes up ‘Santa.’ "

The 'Ticket to Paradise' star previously admitted he was shocked to learn that two babies were on the way after initially only expecting one as he confessed to being apprehensive over the idea of becoming a father later on in life.

Speaking on 'The Drew Barrymore Show', he said: "That wasn't part of the plan. Amal's sister has twins too!

"We went to that thing at 12 weeks where they go, there's the kid. [To] look at the picture of the kid. And [the doctor] goes, 'It's a boy.' Then he goes, 'And a girl.'

"And I was like, 'What? It was such a disaster. I was like, 'Are you kidding me?' Now it's the greatest thing in the world. I was terrified then! I was 56 years old and that just sounded terrifying to me!"