A seat bottom assembly includes a seat bottom frame and an anti-submarining device having a pivot shaft and a panel. The frame extends along a longitudinal axis between a front edge and a rear edge and the pivot shaft is mounted on the frame. The panel extends along the longitudinal axis between a front edge and a rear edge and is mounted to the pivot shaft for pivoting movement between a design position and an open position angularly spaced from the design position. The panel opposes forward displacement of an occupant supported by the frame while in the open position. The rear edge of the panel is spaced forward of a midpoint of the frame such that only a forward portion of the seat bottom assembly between the midpoint and the front edge of the frame opposes forward displacement of the occupant when the panel is in the open position.