Cabo Cruz, Southeastern coast of Cuba, is an important site for queen conch development. Within the Desembarco del Granma National Park, a conch fishery is practically non-existent. Research was carried out in 2010 during three climatic periods (rainy, dry and cold front) at three zones (Farito, Guafe, and Laguna) in order to determine density and population structure of the queen conch. Population density varied from 247 ind.ha^-1 at Guafe in the rainy period, to 1767 ind.ha^-1 at Farito in the dry one. Conch population displayed an aggregated distribution in all zones and seasons. The highest density was detected during the dry season (1395 ind.ha^-1) and the lowest in the rainy season (647 ind.ha^-1). Siphonal lengths (SL) and the lip thickness (LT) of 1836 conchs were measured; the SL varied from 87 to 286 mm. An analysis of LT showed that 73% of conchs had a completely formed lip, but they measured less than 200 mm SL, which represents the minimal fishing size in Cuba. Apparently, the conch population at Cabo Cruz is made up by small conchs, with a gradual increase in weight and lip thickness, as they develop into “dwarf” conchs. The dwarf population is probably related to density dependence. A revision of the protected area management plan is suggested, focused on conchs and its sustainable use.