The Lower St. Lawrence Seaway (LSLS) is located within one of the most active seismic zones in Eastern Canada. It is also home to a range of marine mammals in an environment of intensive fishing and cargo shipping. With the dual objectives to better understand seismic hazard and marine soundscape, we conducted two seasons of ocean bottom seismometer (OBS) experiment in the LSLS between 2023 and 2025, complemented by land stations along the shorelines. The OBS recordings show higher noise levels across all frequencies compared to the land broadband stations, with particularly high noise between periods 0.2-2 s and > 10 s on the horizontal components. The period of peak power systematically decreases from ~2 s to ~0.5 s downstream (from west to east), which may reflect variations in riverbed flow rates. Noise amplitude at the long periods (> 10s) correlates closely with tidal cycles, suggesting that tidally driven riverbed currents are the primary cause. We also observe clear Doppler effects in the harmonics and Lloyd’s mirror effect from multipath frequency interference from passing vessels. Ongoing effort focuses on the detection of signals possibly generated by 1) turbulent currents, for example, the large-scale Anticosti Gyre and smaller-scale eddies, and 2) sea ice ridging.