Reaching at the northern most part of the sound, Sydney Inlet, one of Clayoquot's most quiet areas, extends directly south to the coast, roughly 23.5 km. With a 25 m deep sill at the mouth, the bathymetry holds a deep cliff at 65 m deep that drops to an incredible 130 m, between stations 65 and 70 (roughly 15-19 km inland from the coast). The glacial carved fjord estuary has a relatively narrow, mile wide surface north of the meeting between Sydney and Shelter Inlet. Sydney Inlet is a unique and highly preserved region, holding just one cabin used strictly for estuarine and ecological research. Currently, it is being utilized for inlet sound research, capturing the natural acoustics throughout the water and land. Sydney Inlet Provincial Park covers 2,774 hectares of protected old-growth Sitka Spruce (Picea sitchensis) forests, and holds the Sydney River, the largest river that feeds into the Inlet which homes a large population of Chinook Salmon.

Samples were collected for this study on September 12th, 2014. During this time, weather patterns from Tofino Airport reflected a drop in pressure from the beginning to the end of the day with increasing temperature and wind speeds moving into the area. There was no precipitation, however, with mainly clear skies.

Nutrients that occur naturally throughout Clayoquot Sound are regulated by both biotic and abiotic factors. Watersheds contribute a high amount nutrient accumulation in the waters, while tides allow flushing of these nutrients. Additionally, local microorganisms can help mitigate the overall accumulation with nutrient intake for other biological functions. Here in Sydney Inlet, the deepest area lies just north of station 65 reaching to 130 meters below the surface. This glacially carved fjord is bisected by Stewart Inlet and restricts a lot of the flushing action during ebb tides, leaving limited nutrient flushing. High nutrient concentrations can be seen at basin levels in the charts below.

Throughout Sydney Inlet, temperature remained highly stratified at the surface when moving further away from the mouth into the inlet. This is very present after station 63, north of where Shelter Inlet meets Sydney Inlet. Towards the deeper part of the fjord in Sydney Inlet, the water reaches very low, non-stratified temperatures, which represents the lack of mixing and flushing tides. This is evident with signs of low stratification in salinity levels. Sydney Inlet is seen to be extremely salty, with high surface salinity, providing evidence of low freshwater outputs and low precipitation, and high vertical mixing. With high amounts of salinity found throughout the basin, density is relatively higher here than in other areas. Some stratification towards the surface follows trends of temperature, with higher stratification at the least dense area north of station 63. Additionally, these highly salty and dense waters match Shelter Inlet waters, where there is low stratification and nearly no fresh water found at the surface.

As seen in both Herbert Inlet and Shelter Inlet, there is is a shallow sill towards the mouth which induces the low flushing within this deeper area. This is further reflected here by the nearly anoxic environment present throughout the deep basin. This water below the surface is stagnant and deoxygenated. This lack of oxygen and nutrient mixing allows phytoplankton to only live closer to the surface in the photic zone towards the coast. This is reflected in the fluorescence data collected near stations 60 to 64. Transmissivity also becomes lower where there is phytoplankton found, but what is interesting is there is higher percentages of transmissivity at deeper depths than at the surface, even with this highly dense and salty water.