Naomi Watts admits it was both ''really helpful'' and tough portraying a true story in 'The Impossible'.

The 43-year-old actress stars alongside Ewan McGregor as married couple Maria and Henry - who are joined by their three sons on holiday in Thailand when the 2004 Indian Ocean earthquake and tsunami strikes - and while the blonde beauty insists it was beneficial that the film was based on real life events, it also made filming emotionally challenging.

She said: ''You've got a voice of truth that's there to remind you how serious it was, and even if it's not about something as serious as this, just having them give you ideas and references is really helpful.''

Naomi also admits she felt ''pressure'' to do her part justice and ensure the film is as close to the truth as possible.

She explained: ''You feel, 'Oh, they went through all of this, I really need to honour it with as much truth as what it felt like at the time.'

''And with what I'm doing in the film, it will never be the same as what they went through, but you want to get as close to it as you can.''

Naomi was particularly impressed with the performance of Tom Holland, who played one of her sons in the film, so much so she raised her own game to match his.

She added to ''Tom is a beyond gifted actor. He's just a raw, open talent that is just so easy to work with. And Tom, he's inspiring, he kind of lifts everyone's game around him.''

Ewan and Naomi last starred together in 2005's 'Stay', and the actress was happy to work with the 'Moulin Rouge' star again.

She explained: ''We have a really nice rapport with each other.''