The chemical fingerprinting approach to environmental assessment is illustrated in the evaluation of marine oil pollution on the coasts of the suburb of Florya (Marmara Sea). The samples of unknown origin collected during three leg expeditions on April 2003, December 2003, and February 2004 were analyzed by gas chromatography coupled with mass spectrometry (GC/MS). Hydrocarbon distribution patterns of samples indicated different known and unknown origins. The group hydrocarbon compositions of the samples from leg one are the same as those from the cargo oil spill of tanker Volgoneft-248, which ran aground after structural failure. When it broke apart at the end of the year 1999, tons of oil were spilled into the Marmara Sea. The results show that the remainder of the buried oil in the seabed may come ashore during strong onshore winds even after comprehensive clean-up operations and after 4 years. On the other hand, the samples collected during legs 2 and 3 appear to be from unknown sources.