Great report. One of the names on our village war memorial is that of a sailor who died on HMS Repulse when it was sank by the Japanese along with the `Prince of Wales`. His name was Charles William Hiscox, aged 21 yrs. He was an Engine Room Articifer 4th Class, which meant he was probably in the bowels of the Repulse when it was hit, and never stood much of a chance of surviving. No doubt his remains are still aboard the wreck. What makes it even more evocative is that my mother knew him and they used to go to school together. Up to recently, he still had relatives that lived locally.
A few months ago, I spoke with Dan Stevenson who dived with the Royal Navy team some time ago using an Inspiration rebreather. He reported that the conditions were much as you described them.