Microplastics (MP) pollution has emerged in the last 10 years as an interesting topic of research worldwide. However, microplastic pollution is a new multidisciplinary subject that encompasses many unknowns and enters different fields of science. Research carried out in Turkey on the subject is quite limited and remained on a small scale covering only several stations most of the time. This paper aims to study microplastics distribution, type, and color in 43 stations within the Marmara Sea. The novelty of this work is due to the selection of the stations which cover marine (MRN), pier (PIER), stream (STR), sea discharge (SD), and deep-sea discharge (DSD) stations. The effect of the seawater physicochemical characteristics on microplastics distribution was statistically studied using the Pearson's product momentum correlation coefficient. The highest microplastics abundance was for pier stations (3497016.943 particle/km2) and the lowest was for marine stations (276185.7144 particle/km2). [ABSTRACT FROM AUTHOR]