So, what do you do when a 5 -6ft bull shark...

[Hetland]

Sharks do not have swim bladders. They actually have little need for one since cartilage is so much lighter than bone. Sharks maintain their position in the water column by moving forward and producing lift like an airplane. Sand Tiger's do surface to "gulp" air, however the reason for doing so has yet to be unequivocally demonstrated, but some researchers feel that it is coupled to their unique hunting strategy that requires neutral buoyancy.

The one I saw would hover on one side of a wreck, and looked to be hitting fish as they crested the upper edge (they couldn't see him until it was too late). He left, but was in the same spot doing the same thing on our second dive. Seems to me like it was a pretty good strategy.

 

[SharkDiver36]

Thalassmania is correct.

Sharks do not have "swim bladders". They swim, the fins do provide lift, otherwise they'd sink.

I misspoke on by bladder comment.

Thanks for the correction Thalassmania.