Naturalness is one of the most studied concepts in spatial planning; it is considered an important criterion, especially for nature conservation. The objective of assessing naturalness is to identify landscape character and quality and to set conservation policies. Within this scope, vegetation is one of the primary indicators of naturalness. Human activities alter the naturalness of landscapes, and there is a need for analyzing landscape characteristics of threatened environments since their ecological importance is generally neglected during spatial planning and development processes. This paper aims to assess the naturalness of the coastal landscape along the Eastern Mediterranean region of Turkey, which has undergone rapid changes due to human activities such as tourism, intensification of agriculture, and spreading of settlements. Vegetation analysis and landscape characterization methods are used to assess naturalness. Phytosociological data acquired from vegetation analysis are incorporated into landscape characterization. Eleven landscape types are identified in the study site. Near-natural units covering 64.6 ha, which represent almost 20% of the total threatened area, are concentrated north of the Kizkalesi district. The role of naturalness assessment in spatial planning is highlighted, and an overlying pattern with actual physical plans and landscape units is evaluated and criticism given.