This is a privately owned lake beside the B4418 which has a rather complex shape and a small island in the centre, which is not uncommon in highly glaciated areas. There is a curious story attached to this lake. Once upon a time Llyn-y-Dywarchen had an additional floating island. Giraldus Cambrensis in 1188 told of the lake ‘having a floating island in it which is driven from one side to the other by the force of the wind’. His explanation at that time was perfectly rational. ‘A part of the bank naturally bound together by the roots of willows and other shrubs may have broken off and being continually agitated by the winds….it cannot reunite itself firmly with the banks.’

The astronomer and scientist Edmund Halley swam out to the island in 1698 to verify that it did indeed float.

Thomas Pennant in 1784 claimed to have seen the island and confirmed that cattle which strayed upon it when it was near the shore were occasionally marooned when it began to move.

The island is no longer there, and its legend has died….unless another knotted clump of the bank detaches itself and floats around in the future.