I'm writing a book where the main character knows Tae kwon do (I obviously do not!) and could use some help with pressure points. If fighting someone almost twice your size, what pressure points would be available from the waist up (preferrably in the waist or side) that would cause your opponent to double over helplessly? (Am I asking for too much??) Also, they are fighting underwater. Any tips on how to apply the pressure, using one hand if possible, and where, as well as the affects would be greatly appreciated! Thanks for your help!