We investigated Polyphosphate (polyP) cycling in a cross-latitudinal section (15°N-39°N, 150°E) of the Northwest Pacific Ocean, covering a diverse nutrient gradient and varying P stress conditions in 2023. This data set includes biogeochemical parameters as follows: polyP, chlorophyll a (Chl a), nutrients, alkaline phosphatase activity (APA), picophytoplankton, total particulate phosphorus (TPP). We used a conductivity-temperature-depth (CTD) instrument cluster (Seabird 911) to collect seawater samplers. Seawater samples were filtered onto GF/F filters to obtain polyP and TPP samplers. PolyP was quantified using a fluorescence method according to the protocol described by Martin and Van Mooy, 2013. TPP was converted into phosphate and quantified using a UV spectrophotometer (Shi et al., 2019). APA was calculated through the change of fluorescence using a Turner Trilogy fluorometer (Jin et al., 2024). Nutrient samplers were filtered through syringe filters (0.45 μm in core size) and determined by a QuAAtro Continuous-Flow Analyzer (SEAL Analytical) (Grasshoff et al., 1999). Chl a samplers were filtered onto Whatman GF/F filters (47 mm in diameter) and were determined using a Turner Trilogy fluorometer (Strickland & Parsons, 1972). Picophytoplankton was determined using a Beckman CytoFLEX Flow Cytometer (Wei et al., 2020).