Shifting to renewable energy is an important global challenge, and there are many technologies available to help reduce carbon dioxide emissions. Seawater air conditioning (SWAC) is a renewable ocean thermal energy technology that will soon be implemented in Honolulu, Hawaii, on the island of Oahu. The SWAC system will operate by using cool water from 500 m depth in a heat exchange system and then will release this nutrient-rich water back into the ocean at a shallower depth of 100–140 m. The introduction of a plume of warmed (but still relatively cool) deep seawater has unknown impacts on the tropical marine environment. Possible impacts include increases in primary production, changes in water chemistry and turbidity, and changes in the local food web. We used moored instruments and shipboard profiling to describe oceanographic parameters at the future SWAC effluent site. Parameters varied with the M2 internal tide, and denser water was correlated with higher nitrate, lower oxygen, and lower chlorophyll a (correlation coefficients 0.55, –0.58, and –0.75, respectively). The nitrate concentrations in the plume will be >30.0 µmol kg–1, while ambient concentrations range from