We analyze whether landlocked regions are systematically poorer, using panel data for 1,527 regions in 83 nations from 1950-2014 and exploiting within-country-time variation. Lacking ocean access decreases regional GDP/capita by 13%. Specifically, coastal distance matters but not the length of coastline. Exploring moderators, national political institutions appear irrelevant while increasing international trade and manufacturing intensifies the landlockedness curse within the same country and year. However, transport-related infrastructure may be able to alleviate these disadvantages.