It begins with a disaster, a huge one witnessed not from a distance, not via the safety of a TV news report, but up close and personal.

The horror of the Indian Ocean tsunami of 2004 is made intimate, so awful that you recoil from the screen, ducking as tree limbs and shards of debris are hurled at you and the onscreen victims in “The Impossible.” The effect is akin to being stuffed into a washing machine filled with brown water and about 400 things that can poke, puncture, slice and lacerate you.

While you don’t drown.

Then, stripped, battered, injured and doomed to infection, you try to save yourself and then others. You look for help. You find yourself depending on the kindness of strangers, people who don’t speak your language who are suffering and lost, too, for your very survival. And having children in your care, you try to cling to your humanity as you all cling – barely – to life.

“The Impossible” is a vivid recreation of a disaster made moving by a stellar cast, a gripping, “How will this end?” script and all-too-real special effects and sets. You’ll feel you’re in that oceanic washing machine with Naomi Watts, grieve for her chances of survival and cry over the life lessons she struggles to pass on to her son (Tom Holland).

A Christmas vacation in Khao Lak, Thailand turns terribly wrong for a family of five, headed by Maria (Watts) and Henry (Ewan McGregor), English teachers living in Japan, enjoying the sun and surf until that December morning when the world was turned upside down and washed away within minutes.

Miraculously, they survive the tidal wave. But they’re separated – dad with two small boys of five and seven years, mom with twelve-year-old Lucas. We follow their stories, separately, each looking for and despairing of finding the other, each facing the awful reality that they may be the last members of their family.

For Maria, that takes on extra urgency as the film unfolds. She’s badly hurt, and the struggle to get Lucas and a small boy they rescue along the way to safety becomes the thing that drives her even as we see her pallor change, her own death become imminent.

Lucas, a frightened, confused and rebellious kid, has staggering responsibilities thrust on him. Mom’s “I’m scared too,” is hardly consolation. He might be all alone in the world at any minute, with no way of reaching even distant relations in the aftermath of this cataclysm.

Meanwhile, Henry frantically searches for Maria and Lucas, struggles to keep his boys with him even as evacuations threaten to pull them all out of the area and remove any hope he has of finding his wife and missing son.

The genius of Spanish director Juan Antonio Bayona’s approach is the myopia here. Bayona (“The Orphange”) lets us see only what the victims see. The chaos of the aftermath, First World survivors hurled into the Third World abyss with everybody else there, is stark and alarming. What they don’t know, not being able to get information, to find loved ones, to let relatives know they’re alive, is maddening.

Bayona spares us little in the detail of the injuries, the ocean that victims vomit up days later.

And Watts, in the best performance in an already illustrious career, makes us feel it all. Maria is never so stricken that she cannot see past her own misery, never more heroic than when she distracts her son by charging him to “Go help people, you’re good at it.” Fading in and out of consciousness, fully aware of her own fate, she’s determined to leave Lucas, if she has to leave him, with that one last life lesson.

The effects make “The Impossible,” based on the true story of a Spanish family caught in the tsunami, wholly credible and real. But Watts and young Holland make us feel it, and make this the most moving, the very best film of 2012.

(Naomi Watts and Juan Antonio Bayona talk about re-imagining “The Impossible”)

MPAA Rating: PG-13 for intense realistic disaster sequences, including disturbing injury images and brief nudity

Cast: Naomi Watts, Ewan McGregor, Tom Holland

Credits: Directed by Juan Antonio Bayona, written by Sergio G. Sánchez. A Summit release.

Running time: 2:02