The Empresa Portuaria de Valparaiso (EPV), Valparaiso's Port Company, in 2004 initiated the master plan for the port expansion. A plan that would definitely separate the sea and the city; putting in danger a World Heritage Site. Alternative designs pretend to balance and avoid conflicts between the port expansion and public heritage space destination of the coastal border. This paper discusses alternative propositions to the master plan for the Port of Valparaiso, offering through three base concepts: the port-city relation; the habitable relation between territory and sea; and the role of urban-maritime design to protect Valparaiso's future.