Porthdinllaen was originally a fishing port, based around a natural harbour at the west end of a bay over a mile and a quarter (2 km) across, and with over one hundred acres (40 hectares) of safe anchorage.

[2] Pig farming was important to the economy of the Llŷn Peninsula, and Porthdinllaen was the main point of export to Liverpool.

Apart from goods intended for the local population and the farmers, Porthdinllaen imported large quantities of salt to create the Nefyn herring.

However, none was eventually constructed:[2] In the 19th century, north Wales lacked good roads, so the sea was the easiest way to access many places.

In September 2004 it posed as a Scottish fishing village for the Demi Moore romantic thriller Half Light.