She fought hydrophobia to make "The Impossible" possible. Hollywood actress Naomi Watts, who plays the role of a real-life tsunami victim in her upcoming film, says it is one of her toughest roles in terms of its emotional and physical demands.

In the film based on the 2004 Indian Ocean tsunami, Watts will be seen as a mother who is separated from her family during the tsunami. Her role is inspired by real life tsunami survivor Maria Belon from Spain.

"It (the film) was both physically and emotionally demanding. Maria has been in touch with me throughout the film. Originally when I met Maria I was incredibly nervous and I didn't know where to begin. I felt like 'I'm just an actor and you have lived through this extraordinary horrendous thing, and I just don't know where to start'," Watts told IANS in an email interview from Los Angeles.

The tsunami, amongst the deadliest natural disasters in the world's history, killed over 230,000 people in 14 countries bordering the Indian Ocean.

"I wanted to be physically fit and have the right amount of stamina," Watts said about the role.

The 44-year-old actress said she is grateful to Maria for helping her understand even the smallest details for the film, which will be distributed by PVR Pictures and released in India Jan 4.

"I am extremely thankful to Maria for being with me throughout the film. She has always been there to help me with every small detail. We spoke for hours and connected very well. She was so expressive that it touched my heart," said Watts.

She admits that portraying a real-life character added to her responsibilities as an actor.

"In Maria's case, I just felt I had this responsibility for her. But she feels she has the responsibility for everyone else that suffered or lost lives. So I took that on board and it was such a big thing. Every day we were being reminded of that. That was really weighing on me, which is a lot of pressure," said Watts.

Shooting in water was especially nerve-wracking, said the actress, who has hydrophobia.

"The underwater stuff was incredibly difficult, and I did not like that at all. It's always nerve-wracking holding your breath," said Watts.

"But we were anchored into a chair with weights on us to keep us down. You had the oxygen tank right there up until the cameras rolled, and you'd push it away and then the chair starts spinning, and you have to do all your arm-acting and head-flipping.

"There was one point when I was about to get out of the chair, and I couldn't get out. It was a technical problem, and it really freaked me out. In spite of having a fear of water, I had to stay in a water tank for weeks. (So) it was quite physically demanding for me," she added.

Watts has already bagged a Golden Globe nomination for best actress for "The Impossible" Her portrayal has also created an Oscar buzz.

"It always feels good when your work is appreciated. I am totally thrilled about Golden Globe nomination. Oscar buzz definitely makes me nervous. I do really have a lot of pride about this film," said Watts.

"But the greatest critique I've had is a letter from Maria that came after she saw the film. It was just the nicest letter I think I've ever received. That was so great. I feel like I've done my job," she added.