Sully is a little tidal island off the drift at the village of Swanbridge, halfway amongst Penarth and Barry. It is a little island of only 14.5 sections of land and is uninhabited.
There is a rough interstate interfacing the island to the terrain which is by and large revealed for around three hours either side of low tide. This implies for whatever remains of the day the island is cut off from the territory.
The tide comes in quick so in the event that you visit you should be extremely cautious getting to and from the island.
There is prove that the island was every now and again went to by the two Romans and Vikings and there is archeological proof of a Saxon fortification possessing the eastern end of the Island, on the summit of which is a Bronze Age dump cart.