Was there a bomb and nobody kew it?

[Ed B]

That's good detective work by URI. You don't think about hydrogen being given off in the corrosion process because it happens so slowly. But copper in a corrosive marine environment turning into copper oxide gives off hydrogen. (Cu + H2O = CuO +H2). In this case with a conductive and corrosive material like copper which is encased in a rubber jacketed cable, you have a place for the hydrogen to accumulate. By bad luck some hydrogen must have been weeping out a hole or the end of the cable and the gas met a cigarette. KABOOM.

Hydrogen accumulation is serious business in the submarine world and you have atmospheric control equipment specifically to get rid of it.

I suspect they were very aware it most likely was the cable early on soon after they found it, but just wanted to make sure they had all there info complete before they came out publicly which led to a lot of speculation.