Abstract: A signalling device for signalling danger from water over a low water crossing area is provided. The device has a support post, a message panel, and flashing lights in electrical connection with an energy source, the electrical connection being completed by triggering a switch lever by either a tank float rigidly mounted to a bottom end of a centrally disposed elongate guide member or by a donut-shaped tank float received about the elongate guide member and stopped by a stop member, either the rigidly mounted float pushing the elongate rod upwards and triggering the switch lever, or the donut shaped tank float and stop pushing the elongate rod upwards and triggering the switch lever.