Microplastics are ubiquitous in marine environments as they are found in surface waters, across the water column and in deep-sea sediments. Microplastics could adversely affect marine biota on a cellular level by stretching lipid membranes thereby shortening the lifespan of the organism. The ingestion of microplastics has been reported among larger animals with the risk of neurotoxicity and genotoxicity. In this paper, the likely mechanisms determining distribution and abundance of microplastics in ocean waters and deep-sea sediments have been reviewed. While deep-sea sediment cores reveal high microplastic concentration in ocean trenches and submarine canyons, limited data is available on the abundance of microplastics especially in the Gulf of Guinea. The need for monitoring microplastic concentration and more importantly preventing further transport from land sources is expedient.