Tsunami is a water wave caused due to tectonic activities under water and travels across oceans with very high speed and can inflict great damage to life and property at the shores. The recent Sumatra earthquake of magnitude 9.0 triggered the most devastating tsunami of the recorded history causing a death toll of more than 150,000. Many regions around the globe, especially the Pacific Ocean have witnessed many damaging tsunamis in the past. Countries around the Pacific Ocean have developed an early warning system that has been very effective for the last 50 years. Tsunamis have not been so frequent in the Indian Ocean, therefore lack of awareness has been a major cause for the great devastation caused by the tsunami of 26 December 2004. This feature gives a brief background about tsunamis.