Carreck-a-Rede, on the North Antrim Coast road, is a chasm between the land and a rock island which is 30M deep and 20M wide. Traditionally, the salmon fishermen built a rope bridge between the two, sothey could access a good fishing area. I would guess what we crossed was a much nicer rope bridge and all of the area is owned by the National Trust.
It's a 1 km hike, with lots of steps, to the bridge. Then you have to climb down a metal ladder thing. The views are spectacular!!
We saw gulls and Pigeon Guillimots nesting on what were almost sheer cliff faces. The water was very clear, but we couldn't see any marine life.