The container shipping industry has undergone a substantial structural alteration recently, the main cause of which stems from the enlargement of ship sizes. Previous research on the topic lacked the discussion of the impact of an upsizing policy on the inner operation and management of carriers. Through cognition agreement and decision importance, this study investigated 32 factors that may affect industrial experts whose companies own or order mega containerships. The results of this investigation reveal that cash-flow control, increasing profits, increasing feeders to collect cargo, and gaining competitive advantage are the most determinant factors that affect decision making. European carriers are more concerned than Asian carriers about the potential safety risks in navigation and the trend of persistently ordering megaships. Asian carriers recognize the decreased agility of megaship deployment but strongly dissent from European carriers.