Many submarine engineering, historical and health realities.

Nothing big in submarine-istan today. Soooo, here is a useful Infographic Show video with many submarine engineering, historical and health realities. Don't be deceived by the kiddie-cartoon style.

Perhaps start 1 minute 20 seconds in on spherical submersible vs tubular submarine strengths. Naval submarines must be tubular to house crew, electronics, weapons, to move quickly and hydro-dynamically, etc.

2:05 A submarine must protect its crew by maintaining liveable air pressure. High pressure oxygen
        and nitrogen dangers. [Meanwhile too little Oxygen can cause headaches, eventually death. Too
        much Oxygen - greater danger from static-sparks causing fire/explosion.]

3:03 Subs very limited in diving ranges. "Design" "Test" and "Crush" depths.

3:55 Soviet, now Russian Akula class SSN in the 1980s. [Preceding Titanium Alfa class submarine
        even deeper diving.]

4:01 In response US built the Seawolf SSNs with crush depths maybe over 1,000m

5:22 DSV Alvin submersible secretly [found and raised a thermonuclear weapon (true) and] located
        the wreck of the USS Scorpion (SSN-589) with Scorpion still armed with nuclear torpedoes.

6:15 NASA now very much into deep diving submersible research for Saturn's moon Titan.

Pete