La Corbiere lighthouse is situated off the south west coast of Jersey – an area hazardous to ships because of its rocks and treacherous currents. The lighthouse is linked to the main island by a causeway that is covered at high tide. A siren is sounded to warn visitors of the rising tide. The light from the lighthouse is visible for 18 miles. It was switched off by the occupying forces during World War II and was used only for the convenience of their own convoys.