The use of airborne lidar for aerial surveying and mapping has been growing since the early 1990s, when the first commercial systems became available. It is particularly valuable in the coastal zone, where land and sea meet. In this highly dynamic environment, sand is continually shifted by wind, waves, currents and freshwater flows. Buildings and other structures impeding this natural movement, or even vegetation that stabilises mobile dunes and estuarine sandbanks, typically result in changes to the terrain – both above and below the water surface – over time, sometimes with disastrous consequences.