Photos: MythBusters go under water

Hyneman uses a power drill to drill a hole through a fish that he and Savage will be using shortly to test the fish flapper device. The idea is that the flapper will yank the fish up and down, thereby attracting--or not, as the case may be--a shark. But before the contraption can be used in actual filming, it must be perfected in the MythBusters' San Francisco headquarters.

During the course of the day, Hyneman and Savage go back and forth on whether they plan to use an actual fish at the end of the line or whether it would be better to use some sort of artificial fish-like object.