Sydney Inlet is the northern most entrance of Clayoquot Sound, fed by the Sydney River, the inlet stretches approximately 23.5 km. While glacially carved, Sydney Inlet has a cliff that reaches 65 m and goes as deep as 130 m. The waters of Sydney Inlet support salmon, such as Chinook, and other fish species like rockfish, halibut, and lingcod. Sydney Inlet Provincial Park is about 2,774 ha, which put this area under protection as part of the Clayoquot Sound Land-Use Decision in 1995. The park has old-growth Sitka spruce and Douglas fir. The park also includes Nuu-chah-nulth First Nations heritage sites. Sydney Inlet is considered one of the best examples of a fjord on Vancouver Island.

Samples were collected for this study on September 13th, 2013. Data has been taken from Tofino Airport.

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 seem to be highly stratified at the surface as you continue to move away from the mouth into the inlet. Take note of this 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 of Sydney Inlet. Sydney Inlet extremely salty, with salinity being as high as 31.5 PSU with high surface salinity as well. This shows evidence of low freshwater outputs and low precipitation, and high vertical mixing. With high amounts of salinity found throughout the basin, peaking at 31.5 PSU at a depth of about 28 m, density is also relatively higher here than in other areas in the inlet. Some stratification towards the surface follows trends of temperature, with higher stratification at the least dense areas of the inlet. Additionally, these highly salty and dense waters are similar to Shelter Inlet waters, where there is low stratification and nearly no fresh water found at the surface.

Within Sydney Inlet, there is a shallow sill towards the mouth, indicating that low flushing occurs within the deeper areas of the inlet. The anoxic environment starts to occur at about 70 m. The water deeper in the inlet is deoxygenated and not well mixed. Fluorescence is at about 5 mg/m3 at around 30 m, then drops to 0 mg/m3 deeper into the inlet. Beam transmission is about 70 to 80 percent at 50 to 70 m in the inlet, while the majority of the transmissivity is about 90 percent. When transmissivity is low, this could be associated with where the phytoplankton could be found.