This is a compilation of papers presented at the 6th International Conference on Asian and Pacific Coasts (APAC2011) held on December 14OCo16, 2011 in Hong Kong, China. It contains more than 200 articles addressing a wide spectrum of issues, ranging from conventional coastal engineering problems (such as wave hydrodynamics and sediment transport) to issues of contemporary interest (such as tsunami, coastal development, climate change and seawater level rise, shoreline protection, marine energy, nearshore ecology, oil spill, etc.). Authors present their experiences in tackling these problems, by means of theoretical modeling, numerical simulation, laboratory and field observations, with an aim to advance fundamental understanding of the controlling mechanisms, as well as to develop solutions for practical designs. This volume serves to promote technological progress and activities, technical knowledge transfer and cooperation on an international scale."