Underneath their peaceful appearance, the seas are victims of a profound ecological malaise. The galloping demographic growth of coastal cities, pollution and the worrying influx of tourists are threatening the fauna and flora of these seas. Mediterranean countries often tend to consider the sea as their sewage system: oil, chemical pollutants, waste, tar, metals... they threaten both the marine fauna and flora and the health of bathers. The overall assessment of the effects of accidental oil pollution on the marine environment cannot be immediate, as serious disturbances can extend over several years, while the immediate visible deaths are only the tip of the iceberg. This assessment requires a perfect knowledge of the oil product, its behaviour, its evolution at sea, the fauna and flora, and the physical environment in which it is received. This work addresses the sensitive subject of oil spills at sea, highlighting the dangers of such contamination of the marine environment.