Merlin's Cave

Merlin's Cave is a natural sea tunnel beneath Tintagel Castle in Cornwall, England, connecting Tintagel Haven on the east side of the island to West Cove on the west. At low tide, it is possible to walk from one entrance to the other along a sandy floor. At high tide, the tunnel becomes impassable as it fills with seawater from end to end.

The cave is approximately 100 metres (330 ft) long and was formed by marine erosion along a thrust plane between slate and volcanic rock.

The cave is named after the legendary wizard Merlin, a central figure in Arthurian mythology. This association arises from its proximity to Tintagel Castle, which Geoffrey of Monmouth identified in the 12th century as the site of King Arthur's conception at the behest of Merlin.

Tintagel Island has been associated with Merlin and King Arthur since the 12th century, when Geoffrey of Monmouth's Historia Regum Britanniae (c. 1136) claimed it was where Merlin used sorcery to disguise Uther Pendragon and gain access to Igraine's bedchamber, resulting in Arthur's conception without informed consent.

No medieval texts, however, including those by Geoffrey of Monmouth, Robert de Boron, or Chrétien de Troyes, make any reference to Merlin residing in or being associated with a cave at Tintagel. The name Merlin's Cave did not appear in written records until the late 19th century.

The association of the cave with Merlin appears to have originated during the Victorian revival of Arthurian literature. Alfred, Lord Tennyson's epic cycle Idylls of the King (1859–1885) reimagined Arthur's origin story, describing the infant Arthur being washed ashore by the sea and found by Merlin:

And down the wave and in the flame was borne
A naked babe, and rode to Merlin's feet,
Who stoopt and caught the babe,
and cried 'The King! Here is an heir for Uther!'

Though Tennyson did not name a specific location, later interpreters connected this imagery to the sea cave beneath Tintagel Castle. By the late 19th century, the site had become popularly known as Merlin's Cave, with the name appearing in tourist literature and local guidebooks.