The present invention is a drain plug assembly designed and configured to remain in the drain hole of a conventional pleasure boat, regardless of whether the vessel is in or out of the water. This drain plug assembly includes a body assembly having a single chamber. The chamber houses a shut-off valve for enabling the boater to open or close the drain plug assembly. This will allow water to escape or prevent it from entering the boat, respectively. A safety assembly is included in the chamber. The safety assembly prevents water passage into the boat should the user forget to close the drain plug assembly, prior to placing the boat in water.