Geograph - photograph every grid square

As the name suggests, a lonely rock. The current lighthouse was built in 1904 replacing a previous light.
It is an important navigational aid, as well as something to be avoided. Once the light was on Cape Clear Island, and often obscured by fog/low cloud. This led to the loss of the Steven Whitney hitting West Calf Island. The navigator turned for Cork Harbour, believing the Rock Island light near Mizzen Head was Old Head of Kinsale. The parallel error led to disaster and a new light on the rock was commissioned. The light can be seen at over 27 nautical miles.
Fastnet is famous for being the turning point of the famous yacht race.
This view shows Cape Clear in the distance on an unusual calm summer evening.