High-latitude fjords, very vulnerable to global change, are impacted by their land and ocean boundaries, and they may be influenced by terrestrial water discharges and oceanic water inputs into them. This may be reflected by temporal and spatial patterns in concentrations of biogeochemically important constituents. This paper analyses information relating to the total suspended matter (TSM) concentration in the Porsanger fjord (Porsangerfjorden), which is situated in the coastal waters of the Barents Sea. Water samples and a set of physical data (water temperature, salinity, inherent optical properties) were obtained during two field expeditions in the spring and summer of 2014 and 2015. Bio-optical relationships were derived from these measurements, enabling optical data to be interpreted in terms of TSM concentrations. The results revealed significant temporal variability of TSM concentration, which was strongly influenced by precipitation, terrestrial water discharge and tidal phase. Spatial distribution of TSM concentration was related to the bathymetry of the fjord, dividing this basin into three subregions. TSM concentrations ranged from 0.72 to 0.132 g m−3 at the surface (0–2 m) and from 0.5 to 0.67 g m−3 at 40 m depth. The average mineral fraction was estimated to be 44% at surface and 53% at 40 m.