This is a comparative study dealing with the maritime practices which prevailed in the Byzantine and Islamic worlds around the Mediterranean from 7-10 centuries C.E. and consists of seven chapters. The first chapter describes the physical and legal significance of the ship, computation of capacity, and the importance of naming commercial vessels. Chapter Two examines issues of ownership and possession of a vessel, the employment conditions of the crew, and the passengers’ status on board ship. Carriage of cargo by sea and forms of contracts, liability of the lessor, shipping fees, and breach of contract are covered in Chapter Three. Jettison, average, and contribution are treated in Chapter Four. Chapter Five treats the laws of collision and the rules governing the salvage of jetsam, are surveyed in Chapter Six. The final chapter explains the legal differences between Byzantine and Islamic mercantile law and outlines the principles of the sea loan, chreokoinonia, and qirad.