make a cartesian diving squid in a bottle

Step 6:

fill the water to the very top of the bottle and put the lid on TIGHT. Squeeze the bottle and play with your new diving squid friend! He's even awesome at night, I contemplated giving it to my daughter to play with as a night time toy, but was reminded by my much wiser (and older) husband that it probably wasn't a well thought out idea, as she is 2.5 years old.

**OH! I originally did this with a 2L pop bottle (yes, pop, I'm Canadian) but it was really hard to make him dive, so I swapped it to a 500ml bottle and that fixed the problem


So obviously the 'science' in this is buoyancy and density, if it really boggles your mind you can read more about traditional cartesian divers here: http://en.wikipedia.org/wiki/Cartesian_diver yeah yeah it's a wiki link but it seems to have all the right info.
Go, be with squid, be with bliss

Here is the little guy in action!