Abstract: An inspection drain plug that is removably connected to an aperture in a fluid reservoir. The drain plug comprises an outer hollow body having an open first end and an open second end, the first end being removably connected in a fluid flow relationship to the aperture of the fluid reservoir. A valve mechanism is connected to the outer body, such that the valve mechanism may be selectively operated between an open and closed position, so that the first end of the outer body is closed when the valve is in the closed position. The drain plug also comprises a biasing mechanism, whereby the valve is biased toward the closed position. The first end of an inner hollow body, having an open first end and a closed second end, is removably inserted within the second end of the outer body. Upon insertion of the inner body within the outer body the closed second end of the inner body operatively engages the valve, thereby selectively moving the valve between the closed position and the open position.