OK, barring any other documentation, the list I gave previously should cover the majority of the environment. Depending on the criticality of the system in question to the operation and survival of the sub, MIL-S-901D might be the biggest hurdle, since we're generally talking about shocks in the hundreds of g's.
Otherwise, a submarine environment is relatively benign, i.e., controlled temperatures, no sand/dust, no solar, no rain, etc.
Best of luck...
TTFN
FAQ731-376