In this study, the influence of the artificial configuration on the biota in the Marina and surrounding region in the western inner part of the Fethiye Bay by means of biodiversity and hydrographic characteristics of the region is determined. 15 SCUBA and 3 skin dives have been performed in a zigzag manner to determine the marine biodiversity and detailed distribution of the facieses and different depths and substrates were examined. There is a thin and relatively less saline surface layer rich in nutrient and organic material in the study region. This layer also contains high organic materials which indicates terrestrial input due to fecal coliform. In addition weak current velocity causes accumulating high of suspended material in the water column as visibility is very low in the bottom. According to current measurements during the study period, current velocity with 3.4cm/s is very weak, and its direction is mainly northeast and east. In these negative conditions, biodiversity and natural ecosystem of the bay is damaged in long term seriously.