Been in there a few times! Its a pretty long cave as I remember - although you tend to remember everything being bigger from when you were young.
Took the boat to the beach right at the back and got out - think my name is carved in the back somewhere. There was an old bull seal lying there when we when in. Pretty spooky in the dark. He went in the water as we approached the back but stayed real near the boat and followed us for a good distance back to Leebotten.
My neighbour is moving up in a few months to be the manager of the new Total terminal at Sullom so I'll definately make the trip happen 2012/2013.