An image generating device for a water-surface movable body, the image generating device comprising: an imaging device installed on the water-surface movable body and able to output an image that includes a water surface portion; a position acquiring module configured to acquire positional information indicative of a position of the water-surface movable body; a posture acquiring module configured to acquire posture information indicative of a posture of the water-surface movable body; an additional display information acquiring module configured to acquire additional display information including information indicative of positions of a plurality of locations; a display data generating module configured to generate three-dimensional display data for displaying a graphic indicative of the additional display information by superimposedly placing the graphic on a water surface portion of an image outputted from the imaging device based on the positional information, the posture information, and the positions of the plurality of locations included in the additional display information acquired by the additional display information acquiring module; and a display outputting module configured to output the graphic rendering the three-dimensional display data, the image generating device further comprising: an imaging position setting module configured to set an imaging position that is a position of the imaging device on the water-surface movable body, wherein the display data generating module generates the three-dimensional display data for displaying the graphic based on the imaging position. an imaging device installed on the water-surface movable body and able to output an image that includes a water surface portion; a position acquiring module configured to acquire positional information indicative of a position of the water-surface movable body; a posture acquiring module configured to acquire posture information indicative of a posture of the water-surface movable body; an additional display information acquiring module configured to acquire additional display information including information indicative of positions of a plurality of locations; a display data generating module configured to generate three-dimensional display data for displaying a graphic indicative of the additional display information by superimposedly placing the graphic on a water surface portion of an image outputted from the imaging device based on the positional information, the posture information, and the positions of the plurality of locations included in the additional display information acquired by the additional display information acquiring module; and a display outputting module configured to output the graphic rendering the three-dimensional display data, the image generating device further comprising: an imaging position setting module configured to set an imaging position that is a position of the imaging device on the water-surface movable body, wherein the display data generating module generates the three-dimensional display data for displaying the graphic based on the imaging position. an imaging position setting module configured to set an imaging position that is a position of the imaging device on the water-surface movable body, wherein the display data generating module generates the three-dimensional display data for displaying the graphic based on the imaging position.