The 2004 Indian Ocean Tsunami, one of the deadliest disasters in recent history, claimed more than 220,000 lives across 14 countries. Tsunamis are unpredictable and can arrive within minutes or hours, impacting multiple ocean basins. In response, UNESCO and its Intergovernmental Oceanographic Commission took the lead in developing a coordinated global early warning system. has developed a global early warning system relying on a dense network of sensors, tide gauges, and regional warning centers

In 2004, a large earthquake in the Indian Ocean triggered the largest tsunami in recorded history. One of the countries hit by the tsunami was Sri Lanka, where the wave caused one of the worst train disasters in human history when it hit the Queen of the Sea passenger line, which was carrying 1,500 passengers along Sri Lanka's west coast. Watch Destruction Decoded on Wednesdays at 8pm on National Geographic UK. | National Geographic UK