Marine transportation plays a vital role in the development of Kepulauan Riau as an archipelagic province. The GRDP 2017 of Kepulauan Riau shows that Batam city contributed the most to the figures, which amounted to 64%, followed by other cities outside Batam at 8.54%, and other districts are only under 10%. This condition might be caused by the lack of connectivity and network accessibility between those areas. The growth of passengers and general cargo in Kepulauan Riau was predicted to increase in the next few years, so there must be an improvement in marine services. This study aims to determine the conditions of connectivity for marine transportation in Kepulauan Riau using a degree connectivity matrix and a model for calculating the unit costs. The region with the highest passenger connectivity value is Tanjungpinang (0.83), while general cargo is Tanjungpinang and Batam (0.83). The effect of increasing connectivity to existing conditions and the results of an analysis of services between regions that have the smallest unit cost difference is Karimun-Bintan (IDR 6,881/ton or USD 0.48/ton), and the most significant difference is Natuna-Lingga (IDR 1,568,442/ton or USD 110.26). In terms of time, the slightest difference is Batam-Natuna (3 hours), and the most significant difference is Bintan-Lingga (1,001 hours).