So, how does it all work?

If any of your friends ask how it works, give them this to read.  It will explain it all.

http://www.google.com/patents/US20120102938

I understood this bit.

"From the foregoing, it is evident that the buoyancy actuator according to the present embodiment provides a float which is relatively lightweight and which can be rendered effectively inoperative in adverse conditions for preservation."