The little lappings of water washing up to the shore grows. It grows a bit louder and a longer. It touches your toes, then your bare feet, then the person behind you, till it's gone too far. A bit strange, yes? But nothing to be afraid of. Until the little lappings pushes back one more time and it brings the waves along with it.
And you start running.
Run from the waves that follow you on to shore. It follows you to the bay then to the nearest street then to the buildings. It chases, ready to swallow up anything its path. The wave that is now a tsunami is a monster.