1 : A method for identifying clutter in side scan sonar imagery of a seafloor, the method comprising the steps of: calculating an upper threshold and a lower threshold for each scanline in side scan sonar imagery, wherein pixels in the scanline with a sample value above an upper threshold are brights, and pixels in the scanline with a sample value below a lower threshold are shadows; examining the scanlines to detect runs of the shadows followed by runs of the brights; and identifying the clutter when the shadow falls away from nadir, the shadow has an adjacent of the brights closer to the nadir, and the length of the shadow is consistent with a size of a preselected object.