You can make your own popsicle molds or use reusable molds. Add just a little blue food coloring if you want the shark to be swimming in "blue water".
Make your own popsicle molds
- made according to package directions
Blue food coloring
Pour the kool-aid into the popsicle molds
Add a shark to each mold
Freeze overnight (or until frozen)
The sharks will "melt" a little bit in the liquid, but if you don't disturb them too much they should still look like sharks.