BASILIKOS (Kalin Dimitrov – kalin.d@abv.bg, Nayden Prahov) Underwater explorations were carried out in the bay of Tsarevo, including geophysical survey and diving. The earliest archaeological finds from Tsarevo so far were discovered around St. Mary’s Dormition Church in Vasiliko Quarter and dated to the 5th – 4th centuries BC. Lead and stone anchor stocks dated from the 5th century BC onwards, or perhaps earlier, were discovered along the sea shore in the region. Late Antique and Mediaeval settlements were also situated in Vasiliko Quarter. In 2018, a detailed bathymetric survey with a multi-beam echo sounder was carried out and a model of the bottom with a resolution of 50 cm by 50 cm was created. Side-scan sonar imaging was also performed. A georeferenced mosaic of sonar images was created. Detailed diving surveys were carried out and Late Antique sherds were discovered.