The Kastri lighthouse marks Othoni's western shore and is the northrnmost Ionian lighthouse. The light is obscured by trees that have grown up on the island of Errikusa. The conical white tower rises from a square dwelling. It was damaged during World War II by bombs and looters and was unlit from 1941 until 1954. The kerosene beacon was then restored and served until 1985 when it was electified. At this writing , four resident keepers maintain the light.They are armed to protect the Greek border from intruders.
The lighthouse is not open to the public. The altitude of tower is 13 metres and the height of focal plane is 106 m.