Sully is a village in the Vale of Glamorgan.
At low water (when the tide is out) walk over to Sully Island, a small tidal island at the hamlet of Swanbridge, Vale of Glamorgan, four hundred and fifty metres off the coast. Access to the island is on foot at low tide from the car park of the Captain's Wife public house.
The eastern end of the island features remains of a Saxon fort with a Bronze Age barrow at the highest point. On the foreshore facing the mainland you can see the wreck of a wooden ship at low tide.
WARNING: Sully Island is only accessible on foot from three hours before until three hours after low tide. Remember to come back before the tide comes back in otherwise you will be stuck for 6 hours! In no event try to cross if the rising water is cutting you off - tides off this part of the Glamorgan coast are some of the highest in the world, many people have been swept to their deaths while trying to leave the island as the tide rises very rapidly.