Maritime transport is the most common form of transport and therefore directly impacts on economy, economic growth, global markets and supply chain performance. However, recent incidents such as the Corona pandemic or the Suez Canal traffic jam show that supply chains are as fragile as they are important. Various disruptions put the maritime industry and container traffic into a critical situation. In combination with increasing environmental awareness and the associated use of new technologies, transport costs are at an all-time high and supply and demand are no longer in balance. In times of increasing market instability, successful transport of import and export – and thus the competitiveness of countries and companies – is of great importance. Transport service providers, as the links in the chain that have to facilitate the transport, are therefore under constant pressure to adapt to changing conditions and to not hinder the performance of the entire supply chain. In order to be able to react proactively and early enough to shifting circumstances, industry developments must be recognized and analysed as soon as possible and transport processes need to be optimized accordingly. Manufacturing companies, as one of the most important buyers of maritime transport services, ultimately determine the target values of transport processes in their function as shippers. The aim of this work is to identify and analyse maritime transport developments in the inbound logistics of manufacturing companies and to interpret them regarding their importance for future transport services. After a theoretical overview of global supply chains and supply chain management, relevant influencing factors on the purchasing process of transport services are identified in a systematic literature research. Based on a Delphi study, the questions of how 19 factors affect the purchasing decision of maritime transport services is examined and answered. A panel of experts evaluates the factors that include environmental, quality, cost and time aspects of the transport service as well as other essential performance characteristics. In order to gain deep insights and to forecast future trends in upstream supply chains, three key topics are investigated. Findings from these questions show the changing aspects considered when shippers purchase maritime transport services, as well as essential characteristics for freight forwarders to be competitive in future markets.