A buoy currently marks the position of the Runnel Stone. It is topped with a flashing light and a bell which peals with the movement of the waves. It is also fitted with a whistle set in a tube, which emits a moaning sound when there is a good swell running. This mournful noise can be heard clearly from Gwennap Head, drifting in from the sea, and adds to the eerie atmosphere of the clifftop in foggy conditions.
There are a pair of cone-shaped navigation markers on Gwennap Head, in line with the Runnelstone buoy. These are day markers warning vessels of the hazard of the Runnel Stone. The cone to the seaward side is painted red and the inland one is black and white. When at sea the black and white one should always be kept in sight in order to avoid the submerged rocks nearer the shore. If the black and white cone is completely obscured by the red cone then the vessel would be directly on top of the Runnel Stone. The black and white landmark was erected by the Corporation of Trinity House in 1821 - an event recorded on a plaque on the back of the marker.
One nineteenth century attempt to attach a warning buoy to the Runnel Stone was led by the naval Lieutenant Hugh Goldsmith (nephew of the famous poet Oliver Goldsmith) aboard the cutter HMS Nimble. After several unsuccessful attempts Lt. Goldsmith and a number of his crew turned their attention inland and succeeded in toppling the famous Logan Rock from its precarious perch on the Treryn Dinas headland east of Porthcurno.