Floodplain forests are important ecosystems for biodiversity conservation and carbon storage, yet the relationships between soil organic carbon (SOC), soil physicochemical properties, and floodplain hydrological conditions remain insufficiently quantified in many protected wetland forests. This study evaluated the relationship between SOC and selected soil properties in the Igneada Floodplain Forests National Park (IFFNP) in northwestern Türkiye. A total of 52 soil samples were collected from the study area and analyzed for salinity, pH, lime, nitrogen, phosphorus, potassium, calcium, magnesium, sodium, iron, copper, manganese, zinc, and soil texture. Organic matter was determined using the modified Walkley-Black wet combustion method, and SOC was calculated from organic matter using the conventional Van Bemmelen conversion factor. Spatial patterns of soil properties were mapped using kriging interpolation, and relationships among variables were evaluated using Principal Component Analysis and Pearson correlation analysis. The first two principal components explained 62.16% of the total variance. PC1 was negatively correlated with SOC, whereas PC2 was positively correlated with SOC, indicating that SOC distribution was associated with a combined gradient of chemical and textural soil properties. Spatial maps showed that SOC and nitrogen tended to increase around wet and hydrologically influenced zones, particularly around Mert Lake. The results indicate that salinity, pH, magnesium, calcium, and textural characteristics are important factors associated with SOC variability in the study area. The results provide site-specific information for carbon-oriented soil conservation and floodplain ecosystem management.