when they went down to the sea,tilly saw that something was wrong.the water was all frothy ; said tilly . It was bubbling.tilly remembered a short film her class had seen at school about a massive wave called a tsunami. In the film the sea became frothy just before the tsunami struck. Tilly knew that a tsunami was coming. She began to scream at everyone to get away from the beach. Minutes later,the Great Indian Ocean tsunami struck the coast.