The theory of contestable markets suggests that the presence of limited number and large-volume firms in a market may not be a disadvantage in terms of market efficiency. Contrary to traditional approaches which accept concentration and scale economies as a source of monopoly power, the theory of contestable markets has not seen these factors as an obstacle to effective markets. Within the scope of the theory, it is considered sufficient for high industry efficiency that the entry and exit to the market are completely free Empirical and theoretical studies have been carried out for many types of markets under the theory developed at the beginning of the 1980s. In this study, the theoretical infrastructure of the Contestable Markets model is explained and the World maritime transport market has been examined in terms of potential competition and sunk cost. As a result of the empirical studies it has been concluded that the market has the basic features of the Contestable Markets model.