In every country air does the same thing in the water: it floats, that is - it goes up.
Your SUB bubble is filled with air and as a result - it floats too.
There is a scuba tank on the front of the SUB that provides a constant flow of air into your bubble. This air flow ensures that the bubble stays full of air - even as you descend under the water.
Similar to an inverted glass in water, the air cannot escape unless you tilt it. Your SUB cannot be tilted because a battery and weights are built into the bottom of the unit. Combine that with the air in the top (pulling up) and your SUB becomes extremely steady. In addition, you are tethered to the surface by a buoy.
