'Penmon Point, also known as Black Point, or Trwyn-du in Welsh, is situated on the south east corner of Anglesey and overlooks the Menai Strait, the Irish Sea and Puffin Island. The name derives from Welsh: pen (which can mean "head", "end" or "promontory") and Mon, which is the Welsh name for Anglesey. Panoramic views across the Menai Strait include stretch across the Great Orme to the often cloud capped mountains of Snowdonia. The sound between Puffin Island and Penmon Point is treacherous. A ship named the Rothesay Castle, which was on a day trip from Liverpool, was wrecked in the sound in 1831. The Trywn Ddu Lighthouse (NPRN 308191) and a lifeboat station were erected soon after the incident.
Source: http://www.snowdoniaguide.com, accessed on 17th July 2018.