The study was carried out to assess coastal water quality using multivariate statistics. The coastal water samples were collected in the dry season (March) and wet season (September) in 2020 at eight districts, 26 positions (KG1-KG26). The parameters of temperature (T), pH, salinity (Sal), total suspended solids (TSS), dissolved oxygen (DO), chemical oxygen demand (COD), ammonium nitrogen (N-NH₄⁺), phosphate (P-PO₄^3-), Coliform, iron (Fe), and silicon dioxide (SiO₂) were used for coastal water quality assessment using national technical regulation on marine water quality (QCVN 10-MT:2015/BTNMT), cluster analysis (CA) and principal component analysis (PCA). The results showed that seawater was contaminated with organic (low DO and high TSS in some locations), microbiological, nutrient (N-NH₄⁺), and metal (Fe). The sea water environmental indicators have seasonal fluctuations in which DO, COD, N-NH₄⁺, TSS in the dry season tended to be higher than those in the rainy season. Coliform in dry season and rainy season were similar. The average value of iron in the rainy season was higher than that in the dry season. COD and SiO₂ were low and not regulated in QCVN 10-MT:2015/BTNMT. In the dry season water quality was classified into six clusters while in the rainy season it was classified into four clusters demonstrating spatial and temporal variation of sea water quality. Seawater in the dry season was affected by three main sources while in the rainy season it was only affected by two main sources. The main indicators affecting water quality in the study area including N-NH₄⁺, Coliform, P-PO₄^3-, TSS, Fe, COD, SiO₂. Further studies need to investigate specific sources that contribute to water quality indicators in order to have a solution to better manage sea water quality in the study area.