Science Buddies: "Ask an Expert"

I need to build a submarine that will rest at the top of the water, sink, and then refloat to the top. I have to use things from home and it can't be asprin, medical supplies, cleaning material or water baloons.

Any suggestions on how to get something to float, sink, and refloat?
Thank you for any suggestions.

I found this site on google.com: http://www.spartechsoftware.com/reeko/E ... PenCap.htm

It should help.

Good Luck

Thank you.

Well that's a very interesting school assignment. This link is quite good, I took a look on it myself and I found some great ideas back there. I would also suggest you to start thinking about doing this project yourself, you could get much more satisfaction this way.