Most of us recognise the calming effect of a walk by the river or along a beach. Victorian doctors used to prescribe the "sea air" as a cure for an assortment of agues and ailments. But while the health benefits of green space are now well known, thanks to the pioneering research of Roger Ulrich and the Kaplans among others, little analysis has been made of "blue space" – the impact of the sea, rivers, lakes, and even urban water features on our health and wellbeing.