I saw that same special on National Geographic and made a point of recording it for further detailed study. One of the things that struck me was when that one diver found the remains of the fireman's tunnel, went in and ended up swimming right into Boiler Room Six. I was aware of accounts extant that indicated the doors were open...supposedly to facilitate the change of the watch, but this pretty much confirmed it. (Unless the missing/open door was rendered that way by the blast wave from the explosion.) It couldn't have come at a worse time and when transiting waters known to be mined and infested with hostile submarines, won't go down in history as one of the brightest moves of the age.