This is just a simple modification of whistling bottle rockets to turn them into waterproof firecrackers.
Materials:
Plastic tube whistling bottle rocket
A couple plastic containers
A bit of tissue
Needle nose pliers
Masking tape
Procedure:
1. Remove powder from bottle rocket following steps here. Be sure not to crack the tube.
2. Pour powder back in. You may want to experiment using the powder from one and the powder of two in each casing. Do not press the powder.
3. Insert fuse and stuff in a bit of tissue or other paper to hold everything in.
4. Wrap the whole thing in tape. Don't wrap it too much, but at least several layers. Do an extra good job around the fuse to keep out water.
5. That's about it! Now you have a quick and easy firecracker that will go off underwater (but it must be taped to something heavy or it will float). You could also use a firecracker to plug the end and give it a double report, but that will probably not work underwater.
One cracker fully taped and one with a firecracker (pic is a bit blurry...)
