Contamination by radioactive elements and their transfer through the trophic chain can have harmful effects on ecosystems and human health, therefore its continuous monitoring is important. The present study aimed to characterize the concentration of radionuclides of natural and anthropogenic origin in marine sediments from three areas in the northwest of Antarctica, Orca Seamount, Admiralty Bay and Mackellar Inlet, in order to evaluate possible risk levels, sources and transportation routes. Measurements were made using a high-resolution Canberra spectrometer and methodological precision and accuracy was assessed by analyzing reference materials certified by the International Atomic Energy Agency (IAEA), SOIL-6 and Moss SOIL-447. The results showed a low concentration of 137Cs activity in the marine sediments, decreasing towards the deep zone, validating the atmospheric pathway as the main transport route for this radionuclide of anthropic origin. The activity concentration of radionuclides of natural origin 226Ra and 40K, confirm the volcanic origin of the region, corroborating the geological evolution stages of the sector, and the changes in the source of material to the mantle. The calculated radiation hazard indexes showed that current activity concentrations of radioactive elements do not pose a health risk. It is important in the future to improve the understanding of the relationship between hydrothermalism in the area and the activity concentration of radionuclides of natural origin.