A method for handling sludge arranged on the bottom (2) of a water filled basin (1), wherein the water defining a surface, is described. The method comprises the steps of freezing the sludge in a portion of the bottom (2) of the basin (1), arranging a closable container (3) in the basin (1) below the surface of the water, which container (3) comprises a collecting filter, moving the frozen sludge into the container (3) to a position above the collecting filter, closing the container (3), and thawing the frozen sludge in the container (3). An apparatus for performing the method is also described.