The present invention relates to a method for acquiring location information of an observation buoy reflecting influence of an ocean current and a method for assessing damage risk relating to spilled oil dispersion of a sunken ship by using same location information. At least one small observation buoy is floated on a target sea area, and a relay buoy collects location information from the observation buoy and predicts ocean current distribution of the target sea area on the basis of the collected information; and the predicted ocean current distribution is applied to a step of predicting spilled oil dispersion in a surrounding sea area so that damage risk relating to spilled oil dispersion of a sunken ship is precisely assessable.