I was there the other week, in the rain and had an explore. However I had left my torch in the car so my exploration mainly invovled creeping along in the dark chucking stones ahead to work out how far the tunnels went. Judging from the sound of my thrown stones, they are pretty big (the tunnels, not the stones I threw). I considered going back to get my torch but instead decided to go throw stones on the beach. Stone throwing was a bit of a theme that day.