Current state-of-the-art oil spill models can simulate a comprehensive suite of environmental processes which affect the fate and circulation of oil spills in the marine environment. The degree to which each process can affect the circulation pattern depends on a number of factors. These factors can be categorised in three groups. 1. The initial conditions of the oil spill/oil plume such as the oil type, release depth, leak flow rate, the environmental conditions and more. 2. The predictions of the oil spill model can also vary depending on the chosen hydrodynamic, wind, wave and biogeochemistry data or predictions to be used as inputs for the simulation. 3. The selected correlation to simulate a specific environmental process. Due to the complexity of the transport and fate processes they are typically simulated by simplified theoretical approximations or empirical correlations which can vary significantly in their estimations and as a consequence alter the prediction of the oil spill model to a different degree. In this study we primarily tried to identify: a) the environmental processes that can potentially have the greatest effect on the 3D circulation pattern of the oil spill/oil plume, b) under which initial conditions these effects are pronounced, and c) how sensitive these predictions are to the variability of the initial conditions. We have also touched on the subject of variability due to the selected hydrodynamic and wind inputs as well as the different correlations to simulate a specific process, although we haven’t reviewed all the available input combinations and process correlations. We present the effect of these processes on a single oil spill event and on maps produced by the processing of multiple simulations. Finally, since many of these processes such as the vertical diffusion, vertical advection, particle buoyancy and wave entrainment can only be simulated in 3D oil spill simulations, we compare the predicted 3D circulation patterns with those produced by 2D only simulations.