How is this done?

[sphelps]

I guy could probably use a float switch to activate some kind of vacuum system when the air pocket got to a certain size.

[ElGuappo]

If you look at the top of the tank he has a line drawn at the fill point of the waterline.

I also think this is done wiht mirrors. one scene the fish are in the top half then it cuts and they are all in the bottom. then when they swim under the top part they disappear. you can clearly se the top has a bottom pane of glass.

[untamed]

Originally Posted by lastlight

if you placed a mostly full pop bottle of water into the sink upsidedown quickly, the water would stay in the bottle. Could you not then have an air pump with the input inside the bottle drawing from that air cavity at the top? Blow this air into the bottom of the bottle so it just goes right back where it came from?

That's exactly how I think it works...and that it was very clever to come up with it.

[Black Phantom]

Thanks for that great link. That explains it. Cool concept if you like to take a chance or two.

[lastlight]

However it works it's pretty lame in my opinion!