The Scottish Universities Summer Schools in Physics have been held every year since 1960. The purpose of these schools is to contribute to the dissemination of advanced knowledge and the formation of contacts among scientists from different countries. The lecturers at these schools are all international experts in their subject. Their brief is to present an up-to-date survey of current research in their own field in the form of a coherent series of lectures at a level suitable for students who are normally in their second or third postgraduate year. This volume details and expands upon the lectures presented at the 49th Scottish Universities Summer School in Physics. Written at graduate level, it considers the basic physical processes which occur in the coastal zone, an area in which 60% of the world's population live.