Microplastics (MPs) have appeared as ubiquitous contaminants and pose a risk to aquatic environments as well as humans. They enter the environment from different sources, for e.g., discharge from industries, wastewater treatment plant (WWTP) emissions, breakdown of larger plastic debris, atmospheric deposition, and human activities. Because of the chemical composition of plastics, environments are exposed to both micro-sized as well as nano-sized particles, additives that get leached, as well as degradation byproducts, that living organisms can then take up. They are slowly degrading in soils as well as water which has generated concern among research communities as well as the public. They seriously threaten the aquatic ecosystems and cause physical and histo-physiological damage. Once they enter the environment, they accumulate and persist for a longer duration. They float on the water’s surface. The transportation rate of these particles is higher in the water system. The detection of these particles depends on techniques of sampling, location, and analysis methods. This chapter explores the occurrence, sources, transport, health impact, identification, as well as treatment of MPs in aquatic environments.