This book provides a methodical compilation of deriving composites from the hidden treasure of the aquatic world.Continuous and rapid progress in the composite industries have increased the demand for resilient, economically viable, and sustainable composite materials having enhanced mechanical , thermal and electrical properties which better suits there respective applications.If the materials/organisms used for the production or conversion of composites are renewable, degradable and easily and abundantly available then it gives great opportunity to the researchers to work on different options or processes to make them a viable technology. This work describes the organisms and materials present in the aquatic environment for the production of composite materials. Elaborating the versatile green expedients and their potential applications in the field of composites. Since, growing ecological and environmental consciousness has driven efforts for development of new innovative materials for various end-use applications.Therefore the LCA an circular bio-economy will be discussed to be efficient and sustainable. This book is ideal for the students, academicians, researchers and industry players. It also cover the present scenario, applications and future perspectives of composites derived from aquatic organisms. This compiled book features chapters that discuss the conversion of different materials and organisms present in aquatic environment to composite materials like micro-algae, seaweeds, chitosan, collagen, agar cyanobacteria etc.in a viable manner.