Tsunami: The Aftermath (2006)

S1E1 part 1

While vacationing in Thailand, British tourist Susie Carter makes a horrifying discovery while diving off Khao Lak: a dead body floating in the water. Disoriented, she's pulled back onto her dive boat, only to see more corpses drift past. As they head for shore, the group realizes the entire coastal town has been destroyed. Once on land, Susie and the others frantically search for missing loved ones, but are forced to flee to higher ground, fearing another wave. Under unimaginable pressure, each character is pushed to their physical and emotional limits, fighting to survive while desperate for answers.