Big Green Carr

The rock is easy to identify from the water: look up the channel running north from the entry point and Big Green Carr is the large rock forming the right-hand side of that channel. It is one of several small rocky islands near the harbour, along with Broad Craig and Little Carr, and like them it can be easily circumnavigated underwater. Shore diving from the rocks outside the harbour wall runs to about 15 metres, and trainees use this ground for their first sea dives.

There are walls for much of the way round, and the seaward face is the part to leave gas for: a sharply undercut wall full of holes and cracks, known as the Amphitheatre. The holes are likely to be occupied by squat and common lobsters, velvet fiddler crabs, Yarrell's blennies and, occasionally, the elusive tadpole fish, so it repays working slowly along the undercut with a torch rather than swimming the length of it. The resident wolf-fish is the other reason people dive here, though it is never a certainty on a given day.