This study investigates the drill core 3.00 m in length obtained from DSK-3 drilling carried out in the depth of 10:00 m in the southeast of Tuzla (Istanbul) and in the northwest of Bayramoglu in order to present the marine pollution caused by Dil Stream through the instrumentality of bioindicators (foraminifera, ostracods and molluscs). The purpose of the study is to reveal the adverse conditions caused by the uncontrolled waste disposal from the industry which has been evolving for a long time around Dil Stream located in the provincial borders of Kocaeli. It is not possible under the present circumstances to do any research in the area where Dil Stream discharges into the sea. Therefore, the core obtained from the drilling carried out in Bayramoglu is analyzed by considering the flows in the western portion of Gulf of Izmit. In addition, this study also makes use of the results of the analysis of the samples collected at and around the mouth of the stream by TUBITAK in 2013 for the purpose of demonstrating the environmental pollution in the region. In conclusion, coloration and deformation of the heavy metals and benthic foraminifera which the core samples contain are determined and the adverse outcomes caused by the untreated waste discharged into Dil Stream are demonstrated.