This study aims to report on an inventory of geodiversity features of natural protected sites distributed in the Biga Peninsula in Northwestern Anatolia (Turkey). There are 37 natural sites with their own data sets. Data of the sites describing their boundaries and administrative features were acquired from the national authority. The criteria scale was established for geoscience value for the methodology applied. A conceptual (qualitative) geosite inventory was established for intrinsic geosite potential according to representativeness, rarity, integrity, and scientific knowledge. Then, a semi-quantitative assessment was carried out to compare and parameterize the potential geosites in the scope of representativeness, key locality, geological diversity, rarity, integrity, scientific knowledge, and limitations. From these results, a total of seven sites is highlighted due to their scores for different geodiversity assets. The sites located inland represent endogenous assets labeled lithological, fault, or geothermal, whereas the sites located along the coast are dominated by their exogenous asset (lagoon formation) or simply a geomorphological feature.