I can tell you what's down there Tom

it's reef with alot of holes that you could easily hide a small car in. Seaweed similar to to tassie, and it's pretty deep, well at least it was really dark when I was down there. I've NEVER been sent down that deep that fast, it was instantaneous, freaked the sh@&t out of me. The best bit is when you do make it to the surface your gear is either on the rocks or caught in the channel being sucked out to sea. Leaving you in between a rock and a hard place, literally.