Preliminary results and geological interpretations from an integrated marine geophysical survey for underwater archaeological prospection in the coastal waters of Kiten, Southern Bulgarian Black Sea Coast

The coastal waters around Cape Urdoviza near Kiten, Bulgaria, contain a concentration of submerged cultural heritage, including a prehistoric settlement and several documented shipwrecks, within a geologically complex setting of rocky reefs and sediment-filled bays. This study presents preliminary results from an integrated marine geophysical survey combining marine magnetometry and gradiometry, multibeam echosounding, side-scan sonar, and targeted sub-bottom profiling. The survey covered approximately 4 km2 in two zones north and south of Cape Urdoviza, using reconnaissance line spacing of 50–100 m and denser grids of 10–20 m over selected anomalies. More than 12 localised magnetic anomaly zones, generally 15–30 m in extent, were identified, together with more than 40 small and medium-sized side-scan sonar targets. Two magnetic anomaly zones were examined by divers: one contained a sediment mound without an exposed object, whereas the other yielded ship structural elements. Two additional, partially exposed wreck sites were identified from side-scan sonar imagery. The remaining targets are unverified and are therefore treated as potential rather than confirmed archaeological features. The acoustic datasets also supported a generalised interpretation of three seabed substrate units: rock and reef, mud to sandy mud, and sand to silty sand. Because no contemporaneous sediment sampling was undertaken during the 2025 campaign, these units are considered acoustic interpretations and are compared with previously ground-truthed regional substrate mapping. The broad distribution is consistent with the mapped Kiten Reef and the transition from rocky coastal extensions to sedimentary bay fills reported in earlier studies. The results demonstrate the complementary value of magnetic and acoustic methods for archaeological reconnaissance while also revealing important geological controls on the measured signals. They further show that magnetic or acoustic anomalies alone cannot be equated with archaeological objects without independent verification. The study provides a reproducible preliminary framework for prioritizing future diver inspection, sub-bottom profiling, sediment sampling, and higher-density magnetic surveying in the coastal waters of Kiten.