The Republic of Singapore consists of a main island and approximately 60 small offshore islands.The varied sea-based recreational activities bring many people in contact with marine life. There have been occasional reports of unpleasant encounters with some of these noxious marine creatures. Knowing the harmful species and avoiding contact with them will enhance one's enjoyment of the marine environment. This guidebook features many of the harmful marine creatures present in our waters. It will help people to recognise the potentially harmful species and to avoid contact with them or, if left with no choice, how to handle them with caution. A phylogenetic arrangement is used in this book, where discussion of the harmful marine animals moves from the simple to the complex forms. While first aid treatment is included, the victim should seek medical treatment at the earliest opportunity.