Through examining ships and their design, this book which is part of a series promotes learning through being a "scientist". It is intended that children learn the concepts of observation and create original models from simple materials. The book provides answers to how different materials and shapes behave in water; what displacement is and how it can keep a supertanker afloat?, How submarines dive and resurface; and how sailing boats harness the power of the wind. The text explores athe world of ships from early wood and skin boats to today's powerful speed boats. It explains how ships are designed and built and how to make your own vessels from a Viking ship to a swamp skimmer and an aircraft carrier. The books are designed so as to invite children actively to discover the world around them by making and watching science work. The series was selected by the American Institute of Physics for best science writing for children.