The rupture of a submarine oil pipeline starts various mechanisms leading to an oil spill. Among these mechanisms the leakage of oil driven by the difference in specific gravities of oil and sea-water is difficult to estimate. A simple mathematical model has been developed and laboratory experiments have been carried out to obtain an insight into the buoyancy-driven exchange flow and to determine the leak rate. The mathematical model is predictive and takes account of the effects of friction, inclination of the pipeline, and inertia of the fluid. The experiments were done in a model pipeline at various angles of inclination. Theoretical and experimental results are in satisfactory agreement.