Supermodel Petra Nemcova says it's still 'difficult' to discuss surviving tsunami on its 20th anniversary

Twenty years ago, Petra Nemcova was waking up the morning after Christmas and preparing to leave her vacation in Thailand when disaster struck.

In 2004, Nemcova was 25 years old and vacationing with her fashion photographer boyfriend, Simon Atlee, when a tsunami ripped through their bungalow along the Andaman coast.

A 9.5-magnitude earthquake off the coast of Indonesia caused the world's worst tsunami.

Petra Nemcova recalled the "pain" she still feels 20 years after the devastating Thailand tsunami. (Getty Images)

Atlee was swept away by the waves and not found for three months, and the young supermodel was forced to cling to a palm tree for eight hours to survive.

SUPERMODEL PETRA NEMCOVA RECALLS ‘SPLIT SECONDS’ BEFORE SHE ALMOST DIED IN 2004 TSUNAMI

ABC News’ Diane Sawyer interviewed Nemcova ahead of the 20th anniversary of the tragic natural disaster. 

The now-45-year-old said that the pain of hearing children's screams and not being able to help them is still "strongly" with her "every single day."

"It's always difficult to go back in that moment when my life changed."

— Petra Nemcova

"It's always difficult to go back in that moment when my life changed," she told Sawyer. 

On Dec. 26, 2004, Nemcova and Atlee were staying in Khao Lak, Thailand – preparing to end their trip when the tsunami hit.

Speaking of depending on a palm tree for her survival, Nemcova said, "I went into this stillness, into almost like a meditative state, because I knew if I start panicking, you lose more energy. And I needed all my energy to keep alive."

Atlee's body was discovered and identified on March 3, 2004. He was among nearly 230,000 people believed to have died during the tsunami.

Simon Atlee, Petra Nemcova's boyfriend at the time, did not survive the tsunami. (Photo by George Pimentel/WireImage)

It was a miracle that Nemcova survived. When she was rescued, her clothes had been torn off, and she suffered from a fractured pelvis and internal injuries, GMA reported.

The people who rescued Nemcova were strangers. They gave her clothes, put her on a mattress and pushed her through debris to get to medical aid.

"Those people were ready to risk their lives for strangers," Nemcova said. "And that shows you the best of humanity."

Petra Nemcova clung to a palm tree to save her life. (Photo by Edward Berthelot/Getty Images)

In November, Nemcova told People, "Everything happened in split seconds. I looked up to see frantic movement and people jumping and then in the next second, the wave is crashing into the bungalow and breaking all of the glass windows."

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Nemcova recalled her last moment with Atlee as shards of glass cut into her.

"I heard Simon screaming my name, and it was the last time I heard him."

The model tried to hold on but eventually "let go."

Petra Nemkova and Simon Atlee were packing to leave their vacation in Thailand at the time of the tsunami. (Photo by Michel Dufour/WireImage)

"At some point, I couldn't breathe anymore. And I thought, 'That's it.' That's my last moment. And I let go. And actually, it was the most blissful moment of my life," Nemcova explained.

"And then, by some miracle, I was able to see sky again."

She couldn't feel or move her legs at the time as she listened to the screams of children.

"Half an hour later, I couldn't hear them anymore," Nemcova told People. "And that meant that they couldn't hold on. I couldn’t swim out [to them] because I was trapped by debris. That day, I couldn’t help. I had no choice."

After surviving, Nemcova set out to give back. 

Petra Nemcova founded the Happy Hearts Fund in 2005. (Photo by R. Born/WireImage)

She created the Happy Hearts Fund in 2005 as a way to rebuild schools in areas hit by natural disaster.

"Hearing children screaming for help and not being able to help them, that leaves such a powerful mark," Nemcova explained. "Today and every day, I have a choice to help." 

Since 2005, Happy Hearts Fund has grown into All Hands and Hearts.

The organization will arrive in areas about to be affected by natural disasters to help prepare and then rebuild homes and schools in the aftermath, according to People.

Petra Nemcova flew back to Thailand in 2005 to honor Simon Atlee. (Photo by Richard Corkery/NY Daily News Archive via Getty Images)

Nemcova traveled back to Thailand in 2005 to honor Atlee. The supermodel also chose to face her fear of the water head-on by scuba diving during the trip.

"I went under the water, and I was panicking," Nemcova recalled to the outlet. "My heart was going so fast, and I just couldn't even breathe properly, but it's very important not to live in a life of any fear. That's why I did it."

She admitted it took a few years for "the sounds of palm leaves crashing onto the roof of a hotel or a bungalow" to not reignite her memories.

"And then it lost power over me," Nemcova explained. "If you appreciate the gift of air, if you appreciate the ability to move your legs, everything else is much richer. Your life is happier. You’re living instead of just surviving."

Petra Nemcova will be lighting candles in honor of the lives lost on Dec. 26. (Photo by Jim Spellman/WireImage)

On Dec. 26, Nemcova told ABC News she will be with All Hands and Hearts' volunteers, lighting candles in memory of the lives lost during the 2004 natural disaster. 

"We will invite everybody to join us to light a candle to bring more light to the world," she said.

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Among the volunteers of All Hands and Hearts is Atlee's family.

In 2019, Nemcova married entrepreneur Benjamin Larretche and the couple share a son, Bodhi.

Petra Nemcova married Benjamina Larretche in 2019. (Photo by Gisela Schober/Getty Images)

"I have a son and I have a beautiful husband, and there's so many blessings to be grateful for," she said while noting that Atlee's family has been nothing but kind and loving to her since the disaster.

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"I was lucky, because I met my other twin flame ... Ben is my twin flame, and he is an incredible soul, and I just feel so lucky, because I didn't know it was going to happen," Nemcova told Sawyer.