If your idea of a good vacation means being by the water, visit Sheep Island. Whatever you choose to do here, you're unlikely to get bored of those pretty views.
If you're going to Sheep Island in Ballycastle, leave time to check out other places too. After you've covered off this water-surrounded land mass, Carrick-A-Rede Rope Bridge is nearby and will keep you on the move for a while longer.