Intertidal sediments at Bahia Sucia, on the southwest coast of Puerto Rico contain discreet subsurface layers of petrogenic hydrocarbons. The uppermost of these layers contains petroleum contaminants in concentrations above 200 mg g⁻¹ and is most probably atributable to the 1977 spill from the tanker Zoe Colocotronis. A deeper layer containing a less concentrated load of petroleum hydrocarbons may correspond to the Argea Prima spill of 1962. Sediments above, between and below these two layers present low concentrations of typically biogenic hydrocarbons. Although petroleum released to the sea in tropical environments generally suffers rapid degradation, petroleum contaminants reaching intertidal sediments may exhibit long-term persistence.