He is a leading international researcher in the field of coastal hazards, wave climates, coastal modelling and real-time early warning systems. His research has lead to a number of seminal publications in distinguished journals such as Nature Geoscience, the Journal of Geophysical Research (Earth Surface), the International Journal of Climatology, Coastal Engineering, Geomorphology and Nature Scientific Reports. He has taught short-courses on coastal processes in South Korea, Italy and Australia and given keynote presentations in Brazil and Australia. Recently Dr Harley founded the program CoastSnap, a crowd-sourced beach monitoring technique using smartphones that is now operating in 7 countries worldwide.