Surveys of the oiled sandy beaches along the northern Atlantic coast of Spain, 2-5 years after the Prestige oil spill of November 2002, have provided new evidence regarding buried fuel and its behavior. The persistence and depth of burial of oil, and the capacity of the beach for natural regeneration, depend on beach morphodynamics, which drive a sequence of physicochemical processes that reduce subsurface tar balls to highly divided oil forms while also allowing appreciable weathering despite burial. These findings prompted reassessment of current spill evaluation strategies. A protocol is proposed that combines the modeling of beach morphodynamics, an environmentally friendly coring survey, and well-calibrated hydrocarbon analysis.