St Tudwal's Lighthouse on Saint Tudwal's Island West is active, but unstaffed. The site of the lighthouse, which marks the north end of Cardigan Bay, was purchased by Trinity House in 1876 at the sum of £111 and the next year the stone building was complete. It is 10.7 metres (35 ft) tall, with its focal plane (height of light above high water) at 46 metres (151 ft). The main white light has a range of 14 nautical miles (26 km; 16 mi) and its red sector light has a shorter range of 10 nautical miles (19 km; 12 mi). It gives 1 white and red flash every 15 seconds, the intensity being 12,000 candelas (candle power).

Automated in 1922, it was one of the earlier lights Trinity House automated. It was electrified in 1995. The lighthouse keepers' cottages are now privately owned and used as a holiday home.

The lighthouse building is Grade II listed, as are the lighthousekeeper's cottage and the perimeter walls.

• List of lighthouses in Wales

• Hague, D., B., Lighthouses of Wales Their Architecture and Archaeology (Royal Commission on the Ancient and Historical Monuments of Wales, edited by Hughes, S., 1994) ISBN 1-871184-08-8

• Trinity House
• Video of lighthouse interior and surroundings, late 1980s