Well, there is a fake hatch, remember when Sayid opened the one door at the then deserted Others camp, it had a symbol on it, but there was only the wall of the mountain beyond. that could be the crossed out hatch. Locke was also tied up somewhere, then taken to a room where cooper was, that whole place seemes like some sort of hatch too, not just a basement in Ben's Bungalow of assorted Booty.