Sea transportation is one of the choices for public travel facilities besides land and air transportation. Several factors, both internal and external, affect the decision-making process of individuals when selecting sea transportation as a travel option. Internal factors originate from the customer's personal preferences and circumstances, whereas external factors are influences that arise from outside the individual, playing a role in shaping their choices. The internal factors used in this study consisted of community expectations, the distance of residence to the port and the community knowledge of the services of the chosen ship company. The external factors consist of the number of crew members, the level of security, the availability of prayer facilities and also the discounted ticket prices given. In this study, these factors will be grouped to find out about people's decisions in choosing sea transportation as a means of travel using the Gath-Geva algorithm clustering method. The Gath-Geva algorithm builds upon the Gustafson-Kessel algorithm, offering the capability to identify clusters with a range of shapes, sizes, and densities. It utilizes fuzzy maximum likelihood estimates for distance measurements and incorporates an exponential component to enhance its clustering process. The results of this study are that the majority of users of sea transportation services use services at the port of Java island, namely with a percentage of 46.43% and the remaining 53.57% are outside Java island where people choose to use travel services via sea based on internal factors or factors that come from within themselves, namely service expectations with a classification accuracy of 62.44%.