The Benagil cave is one of the most remarkable geological features on the Algarve coast. A collapsed sea cave has created a vast domed chamber with a circular opening in the ceiling, through which sunlight falls directly onto a small sandy beach inside the cave. The effect is extraordinary — part grotto, part natural cathedral.
The cave is accessible only from the sea. Boat trips from Carvoeiro reach it in about 20 minutes; kayak rentals are also available from Benagil beach, a short drive east. You can land inside the cave on the small beach, though operators vary in whether they allow this. Book trips in advance in summer — it is extremely popular. Early morning boats are quieter and the light is better.