The orientation of Nha Trang Bay is mainly toward sllstainable marine tourism and services. Thus, water quality, specifically total suspended sediment (TSS) takes an important role in marine tourism development. Based on survey results of the 85 dry-season-stations and 72 rainy-seasonstations, secchii disk depth, salinity and TSS were checked. The concentration of TSS varied strongly in temporal and spatial scales. In the dry season, TSS was 0.03 - 5.24 mg/L in surface layer and 0.04-18.49 mg/L in bottom layer. TSS in .the dry season was lower than that in the rainy one with TSS content in surface and bottom layers of 0.57-10.77 mg/L and 0.94 - 27.66 mg/L, respectively. High TSS was found in the rainy season and distributed in waters along the coast, but thank to the quite high deposited ratio of TSS, water quality is better in a short time. In addition, high TSS was also related to eutrophication in Cai and Be river mouths. Although, the concentration of TSS met the environmental standard for swimming beaches (QCVN 10:2008/BTNMT), it negatively impacted on water color, reducing light intensity in water bodies and degradation of water quality. As a result, TSS was as a limited condition of marine tourism services, such as swimming and diving. Therefore, to strengthen sustainable development of marine tourism in Nha Trang Bay, it is important to implement an action plans to reduce TSS in runoff water, as well as to manage waste from economic activities and domestic waste in coastal regions.