It's utterly moronic. Those bunkers and bomb shelters are made to withstand air raids and nuclear bombs, not ground assaults. There is zero chance anyone is spe

It's utterly moronic. Those bunkers and bomb shelters are made to withstand air raids and nuclear bombs, not ground assaults. There is zero chance anyone is spending any resources on bombing a tiny island with a population under 100,000, but those locals? The first thing those locals are going to do if society actually breaks down is find those water and air intakes (that they built!) and shut them down. The latter by lighting a garbage can full of plastic on fire and flushing the inhabitants out. If they actually have an active life support system with CO2 recycling, the locals will just destroy the bunker from the outside because... well... we've been quarrying giant blocks of rock for thousands of years. It's not that hard when you've got unlimited physical access. Even the steel door is a minor barrier when you don't have fortified towers or parapets to defend from. The question is whether the island has enough explosives on it or whether the locals would have to boat over to a bigger one to borrow some. If not, a cheap jack hammer would make quick work of the bunker but even if they were reduced to wood fires and a single pickaxe it wouldn't take more than a few weeks to pick the structure apart using prehistoric techniques: https://en.wikipedia.org/wiki/Fire-setting https://en.wikipedia.org/wiki/Fire-setting