Container ship design has been driven by economies of scale with the search for greater efficiencies in transportation rate per TEU propelling the industry toward ever larger vessels. In only the last few years, the size of the largest vessels has bounded from 14,000 to 18,000 to over 19,000 TEU, and today 20,000 TEU vessels are already on order at several shipyards. In his presentation Jost Bergmann, DNV GL, looks at the size development of ULCS, the main characteristics of 18,000 to 20,000 TEU vessels, the limiting factors to sizes above 22,000 TEU, as well at the considering the surrounding infrastructure, the impact of large container vessels upon it, and a cost/benefit analysis of ULCS. Finally the presentation considers, by applying a holistic perspective to both ship and supply chain, the optimum vessel size.