The approach sets the tone. You drop down a steep wooded valley to a narrow inlet where the sea pushes in against dark slate cliffs, and the beach itself plays a slow game with the tide. At high water there is almost no sand to speak of, just rock and surging Atlantic; as the tide pulls back, a string of smaller beaches joins into a broad sweep that runs the best part of a mile northwards. Because that transformation is so complete, the timing of your visit matters more here than at most Cornish beaches, and it is always worth checking the tide tables before you set off.
Look closely at the cliffs and you read the area's working past. This was the heart of Tintagel's slate coast, quarried since the fifteenth century, and the scarred ledges and old workings between the strand and Tintagel Castle are the remains of an industry that once shipped slate out by sea. Coal came ashore at Port William at the southern end, and sand was carted up the valley to spread on inland fields. That mix of raw geology and quiet history gives Trebarwith a character quite different from the soft, dune-backed beaches further south.
Today it is loved for its drama rather than its facilities. Surfers and bodyboarders come for the Atlantic swell, walkers pick up the South West Coast Path north towards Tintagel and its Arthurian castle, and rock pools open up among the reefs at low water. It is a place for big skies, sea air and a proper sense of the north coast at its wildest, best enjoyed with a respectful eye on the incoming tide.