A sea floor investigation was performed in the fiord of Hornsund by means of the seismoacoustic profiling, echosounding and core sampling. The main seismoacoustic sea floor units were recognized (the methods used according to Kowalewski et al. 1987a) and characterized on the basis of their relations to geomorphology and geological evolution. The bathymetrical sketch and the resulting geomorphological description of the bottom were prepared. The surface of the sea bottom and the surface of the bedrock displayed an irregular high relief with large sills dividing the fiord sea floor into several basins. Four main types of the sills were distinguished: burried sills, accumulative sills, rock sills and rock-accumulative sills. Within the internal Basins I and II there were thick (up to 170 m) covers of the glaciomarine ice-front deposit with changing thin ( 1 -5 m) blanket of the glaciomarine muds at the bottom surface. The Basin III had a cover of the glacial and glaciomarine deposits of variable lithology, genesis and age. The most external Basin IV had a cover o f glaciomarine muds up to 4 0 - 5 0 m thick, deposited on the tills. Four main glacial episodes were recognized, most probably referring to the stadials of Lisbetdalen, Slaklidalen, Revdalen and to the Little Ice Age.