Submarine Argonaute (S636) exposed in la Villette (Paris, France) : double hull. The exterior hull is thin. The interior hull is thick, in order to resist to the pressure. Water is pumped between the two hulls to make the submarine going down.
<a href="//commons.wikimedia.org/wiki/User:Tangopaso" title="User:Tangopaso">Tangopaso</a>
2016-02-25
<span class="int-own-work">Self-photographed</span>