This is the first field guide for the seashore organisms in Penang National Park, Penang, Malaysia to present the magnificent seashore species that make up a striking diversity in this natural environment. The content of this book are largely restricted to the organisms that are most frequently encountered or interesting to be documented; displayed by colour photographs, taken in their natural habitats; their taxonomic positions are indicated, brief descriptions are provided and together with the details of their known geographic distribution (types of habitat and distribution zone). The images in the field guide were also taken with uniform background, with views from the ventral, dorsal, side and close-up (for important identification) to assist the readers/users for clear visual identification of the organisms they encountered. This book aims to stimulate interest in seashore ecosystems and will broaden the general knowledge of the interested layman and the scientific visitor of coastal seashore areas regarding biodiversity. It will also help both institutions and individuals to develop an appreciation of broader environmental concerns.