I don't understand the submarine idea, that is an untested device for cave diving, also human breath from a very localized part of their body, so their is no po

I don't understand the submarine idea, that is an untested device for cave diving, also human breath from a very localized part of their body, so their is no point to pressurize everything, and you keep the flexibility of the body to not have a full metal cylinder around you. If you need to control someone, some anti anxiety pills and a harness are some tested tools for that.