Lake Vortigern

Lake Vortigern is a Lake that is a part of the legend of King Arthur. Tt is said that King Arthur obtained the legendary sword, Excaliber, from the Lady of the Lake whose hand had risen from the Lake holding onto the sword.

At the bottom of the lake was a transdimensional ship, which contained King Arthur's suit of armour, a note from an alternative future Doctor, and an energy creature which functions as the ship's defence system. The ship could be accessed by an underground tunnel. (DW: Battlefield)