The intertidal rocky shore of Skokholm island (SW Wales) is naturally colourful with a diverse benthic community of red, green and brown algae, sponges, barnacles and molluscs attached to red sandstone. In the summer of 2018 there were exceptional weather conditions (caused by a persistent anticyclone over the UK) producing many weeks of sunny, windless days and very calm seas with minimal turbulence and wave action in the intertidal. Light is both reflected off and refracted (light caustics) by the sea surface with small wave peaks and ripples acting as lenses creating bright regions at their foci whereas darker areas are associated with the wave troughs. Detailed aspects of these rapidly changing intertidal visual effects are unable to be processed by the human eye / brain in real time. However, they can be captured photographically and thus fully appreciated by freezing the action with relatively high shutter speeds,