In Croatia, a country with a thousand islands, there is an obvious need for the development of continuous maritime transport connectivity, which is a condition for further economic and demographic development. From an economic point of view, maritime passenger traffic does not provide optimal economic capacity utilization due to its seasonal nature. Various mathematical analyses, models and theories need to be used to find the most favourable solution that will enable the population of the island to live normally, at the same time II minimizing costs and optimizing traffic connections with the mainland and the other islands while taking environmental sustainability into account. One of the theories is the theory of waiting lines, which will be used in this paper to analyze seasonal issues, as well as to find the most favourable solution for optimizing flow during "peak hours" and reducing waiting times. Tourism, the main economic activity on the Croatian islands, is of a seasonal character, so an optimal solution must be found for all seasonal phases. In Croatia, the largest share of maritime passenger traffic is currently occupied by the shipping company Jadrolinija, which promotes its importance and the importance of connections by maritime transport with the slogan “Lifeline.” The presented methodology is analyzed using the example of Jadrolinija and several of its ferry connections.