Abstract: A sport fishing chair for boats is provided with an auxiliary seat assembly which enables a fisherman to utilize a greater number of body muscles while reeling in a gamefish. The chair has a seat portion mounted to pivot on a pedestal, a rod holder in front of the seat portion, and a foot rest carried by the seat portion. The auxiliary seat assembly includes a base member secured to the seat portion of the chair, a support member superimposed on the base member for supporting the body of the fisherman, and means interposed between the seat and base members to afford sliding movement of the seat member from a retracted position overlying the chair seat to an extended position toward the foot rest. A body harness rests on the support member and is connected to the fishing reel. This structure enables a fisherman to move his body back and forth in the chair to pivot the rod and reel by alternately bending and straightening his legs.