This paper analyses the suitability of seas and the attractiveness of shores for the construction of submarine power interconnections. Water depth and distance between shores are considered to assess the suitability of seas, while potential for electricity consumption (estimated through population size and density) and potential for power generation from renewable energy sources are taken into account to evaluate shore favourability. Scores are attributed to these variables by using four classes of suitability. Individual scores are added to map the overall suitability of seas and shores for building submarine power interconnections. It is found that more than 20% of the global surface of seas and more than 40% of the global shore length are highly favourable. Most of the submarine power interconnections built so far are located in these highly favourable areas, confirming the validity of the presented methodology. Accordingly, the study offers a useful tool for planning submarine power interconnections, which play an increasingly important role in ongoing energy transitions.