‘Tsunami’ is a Japanese word that translates to ‘harbour wave’. Sounds pleasant enough, but unfortunately this name doesn’t emphasise the destructive potential of these hazards. When most people think of tsunamis, they picture a wall of water crashing into a coastline. So why is it that in some cases the water is seen to recede to an extensive distance before surging back onto the shore? This phenomenon is known as the Initial Withdrawal of the Ocean (IWO). Confusingly, this spectacle doesn’t take place during all tsunami events and can even occur in certain areas but not others during the same event!