Until May 2012 it was topped with a flashing light, a bell which peals with the movement of the waves and was also fitted with a whistle set in a tube, which emitted a moaning sound when there was a good swell running.

This mournful noise could be heard clearly from Gwennap Head, drifting in from the sea, and added to the eerie atmosphere on the cliffs in foggy conditions.

In October the following year the beacon was snapped off in a gale, leaving a 2 ft (0.61 m) stump (which was itself carried away, following a ship collision, before repairs could be effected).

[4] Various buoys have since been attached, as in December 1880 when the local newspaper (The Cornishman) reported that the Trinity House vessel, Stella put into Penzance with about 30 tons of mooring-chain, etc.

[8][9] When the Longships Lighthouse was rebuilt in the early 1870s, its fixed white light was provided with a pair of red sectors to indicate nearby hazards, one of which was angled towards the Runnel Stone.

[10] On a calm midsummer day during World War I, a Royal Navy minesweeper hit the rock despite a local fisherman serving on board as a rating.

[1] On a foggy day at 3pm, 8 October 1923, the 6,000 ton SS City of Westminster bound from Belfast to Rotterdam with a cargo of South African maize knocked the top of the reef clean off.

[1] Due to its exposure to the ocean currents and its relative accessibility of slipways at Porthgwarra and Lamorna, the Runnel Stone is known as one of the best dive sites in the whole of Cornwall.

[12] The Conservation Zone boundary is a 3.5 km arc based on and to the south of the National Coastwatch Institution lookout on Gwennap Head.

& others, a Captain Lille describes the harrowing passage he inadvertently took with his ship, the barque 'Favell', sailing her between the Runnel Stone and the shore on 5 October 1934.