Trwyn Du or Black Point is situated at the extreme south-eastern tip of Anglesey. The beach of is made up of rocks and some small patches of sand, backed by a storm bank of limestone pebbles and looks out towards Puffin Island (Ynys Seiriol) about 200 yards offshore. The island's Welsh name originates from a monastic settlement established by St Seiriol, some remains of which can still be seen. A lighthouse stands on the intermediate low-tide rocks, and has a bell which sounds every 30 seconds. The only facility at the beach is the Pilot House cafe.
A car park is located just behind the beach, and is reached via a toll road from Penmon Priory - the toll also giving admission to the priory.