Things You'll Need

Instructions

1

Drill a straw-sized hole in the cap of the bottle.
2

Drill three equally spaced holes into the bottle's side.
3

Make three stacks of pennies in the following quantities: four, eight and 12.
4

Tightly wrap each stack with aluminum foil, then set them aside.
5

Put a rubber band around the bottle so that it is near but not overlapping one of the holes you cut in the bottle. Do the same thing with the two remaining rubber bands.
6

Put the four-stack of pennies beneath the rubber band that is closest to the hole near the bottle's mouth. Put the stack of eight pennies under the next rubber band and place the stack of 12 pennies beneath the third rubber band.
7

Insert the straw's short end into the hole in the bottle cap.
8

Screw the the bottle cap onto the bottle and tape the straw to the top. Be sure the straw is upright and flexed.
9

Sit the submarine in water and blow air into the bottle through the straw. This enables the submarine to float as water flows through the holes.