Dude,
Respectfully:
• The “glass” is plexi, and plexi that thick will stop a bullet (& yes I know there is pressure behind it, but it still would take an explosion to quickly bring one of those sheets down
• The “high frequency” thing is complete James Bond
• That amount of water would disapate rather quickly if let loose from the tank, I’m not saying it wouldn’t be a mess and a hassle, but it wouldn’t flood the Land or Spaceship Earth.
I think the simple answer on the Living Seas is it's too expensive to staff the SeaCabs when all they did was give you a short ride with a lower level view (below the area that lets you walk out into the viewing in the round) and they then dumped you out in the same place you are today.