There are rough outlines of how they work on line. The key elements from what I understand are shitloads of batteries, a diesel engine that can charge the batteries during surface cruise, and making sure you don't sink or suffocate. They're really cool. Honestly they give me so much hope by showing that even with all the ridiculous surveillance technology the government has it's still possible to evade detection.
I love how, in the end of the video, the guy said something like "the Coast Guard hasn't detained many true submersibles in open waters". Which to me sounds like most of the newer subs are evading the feds
Also - The history of submarines is really cool. From diving bells, to the famous "What if we put drill on a barrel, swam it up next to a military ship, and tried to drill in to it?" to the Confederate Navy's famous Confederate Killing sub the Hunley, to all kinds of weird shit.
