The Bay of Caska, on the Island of Pag, preserves the remains of a stratified settlement, with an important phase linked to a Roman maritime villa, the property of the senatorial family Calpurnii Pisones. After presenting the geographical and historical context of the site of Caska, the article summarizes the achievements of past archaeological research, and presents the results of the recent research carried out on land and under water. In particular, it focuses on the harbour structures, where the remains of four scuttled vessels were discovered. These vessels, three sewn boats and one mortise-and-tenon built ship, all filled with rocks, formed pier-like coastal structures. The architecture of these vessels is also discussed.