ABC News’ Diane Sawyer interviewed Nemcova in the months after the tragedy. Now, 20 years after one of the deadliest natural disasters in modern history, Petra sat down with Sawyer again to reflect on the horrors of that day, and the kindness of strangers that got her out alive.

Model Petra Nemcova opens up on 'GMA' about surviving the 2004 tsunami that killed 5,000 in Thailand. 'It's always difficult to go back in that moment.'

After surviving the devastating tsunami that struck southern Asia 20 years ago, the supermodel is dedicating her life to helping victims of natural disasters, transforming her pain into action.