An auxiliary deck assembly for a pontoon boat includes a stowable auxiliary deck and mounting structure. The mounting structure swingably supports the auxiliary deck for swinging movement between stowed and operating positions. The auxiliary deck is configured so that the auxiliary deck surface is generally aligned with the primary deck surface when the auxiliary deck is in the operating position. The auxiliary deck is further configured so that the auxiliary deck surface is oriented at a generally upright angle relative to the primary deck surface when the auxiliary deck is in the stowed position.