Hi everyone, It might seem like a silly question but given that 10m of water is about 1 atmosphere, the amount of hydrostatic pressure that deep diving military submarines undergo must present enormous waterproofing & engineering challenges. How is this problem solved? Using metals with large elastic strain capabilities (we are talking about pressure differentials of say 70 atmospheres plus safety factors), waterproof-yet-strain-capable joints, etc.? How are the vessels made? The usual rivet or bolt construction would present a multitude of locations for leaks. Also, at the height of the Cold War when impressive submarines like the Russian Alfa were fielded, I presume the Russians didn't have access to computer hardware and finite element codes back then to do the necessary strain computations. So how did they do the design calculations? Cheers, J.