Marine sediment is a complex solid structure that is an integral part of the marine ecosystem and covers a large part of the Earth's surface. Due to industrial exposure, they may contain various types of pollutants. Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds formed by the combustion of organic matter during various industrial processes. They are among the most significant pollutants because they accumulate in sediments and waters over the years, and heavy metals also have this tendency. The municipality of Kostrena and the associated waters are located in the Primorje-Gorski Kotar County and have been strongly influenced by numerous activities and industries for many years. All this affects the ecological stability of this area. In this research, the emphasis was placed on determining the concentrations of heavy metals and polycyclic aromatic hydrocarbons in marine sediment at locations that are in the immediate vicinity of industrial plants. During the period from 2014 to 2020, the test was performed at a total of 8 points of which 6 were assumed to contain heavy metals and PAHs and 2 which were observed as control points. The analysis determined the presence and elevated concentration of metals and PAHs at all sampling points for which contamination was assumed. The results indicate the need for further research and monitoring of sea sediment as well as the introduction of legislation that would allow better monitoring of such environmental pollution.