Abstract: A small craft plug detector indicates whether a drain plug of a small boat or craft is installed. In a first embodiment a hollow cylindrical housing has upper and lower ends with central openings therethrough. An indicating plunger disposed within the housing has a rod which extends upwardly through the hole in the upper end of the housing and a lower end which extends downwardly through the opening in the lower end of the housing. A spring biases the plunger in an upward direction. Electrical contacts are provided so that an electrical connection may be made to activate a lamp, alarm, or the like when the plunger is moved downwardly. A second embodiment utilizes the electrical contacts of the first embodiment, but has no central opening in the upper end of the housing, and the plunger has no rod portion extending therethrough. A third embodiment of the invention is similar to the first embodiment, but does not include the electrical contacts.