UNDERWATER ARCHAEOLOGICAL EXPLORATIONS AT BIZONE (Nayden Prahov – naydenprahov@yahoo.com, Asen Salkin) The underwater explorations were carried out in front of Cape Chirakman, in the harbor and to northeast of the eastern breakwater, from c. 2 m to c. 10 m below the sea level. A geophysical survey was carried out with a multibeam echo sounder and side-scanning sonar. A detailed bathymetric 3D model and bathymetric maps were produced. An aerial orthophoto shooting was carried out with a drone and a detailed photogrammetric terrain model of the land and adjacent water area was produced. Diving surveys were carried out. In 1961, a wall in opus mixtum was discovered at c. 150 m in front of Cape Chirakman, but in 2020 it was not found. Diving surveys were also carried out in the western part of the small bay between the middle and the eastern breakwaters. During previous underwater explorations, architectural fragments, a head of a marble statue, two bronze trays, sherds, a coin, etc. were discovered there. In 2020, a column drum and dozens of ashlars were discovered, some of them with grooves to accommodate iron clamps. The concentration of these architectural remains indicated the existence of destroyed monumental buildings. In 1969 and 1971, an ancient breakwater was explored in the eastern part of Kavarna Bay; it started 150 m from the shore and was 120 m long. In 2020, the remains of the breakwater were not discovered.