Water waves are a dramatic, potentially dangerous, yet beautiful phenomena that is omnipresent and impacts every aspect of life on the planet. At smaller length scales the ripples driven by surface tension affect remote sensing. At intermediate length scales waves in the mid-ocean affect shipping and near the shoreline they control the coastal morphology and the ability to navigate along shore. At larger length scales waves such as tsunamis and hurricane-generated waves can cause devastation on a global scale. Across all length scales an exchange of momentum and thermal energy between ocean and atmosphere occurs affecting the global weather system and the climate.From a mathematical viewpoint water waves pose rich challenges.The governing equations for water waves are a widely accepted model and they have been the subject of a wide range of research. However, the equations are highly nonlinear and the level of difficulty is so great that theory has yet to scratch the surface of the subject. The solutions to the equations that describe fluid motion are elusive and whether they even exist in the most general case is one of the most difficult unanswered questions in mathematics.On the other hand, there is good reason to be buoyant about the headway that mathematics can make in tackling the great open problems posed by water waves. In light of recent developments the questions are now clearer, new methodologies are emerging, computational approaches are becoming much more sophisticated and the number of researchers at the highest international level involved is growing. All these indicators point to an opportune time to have a focused conference on water waves.