Scuba/Snorkeling Cococay and Nassau

[ajknightfan]

Last minute decision and we're booked on RCCL cruise in July stopping at Nassau, Cococay and Key West. Would like to dive once, and am wondering where the best spot is, and if we should go through RCCL or try to book outside the line. Also, is there an option for scuba and snorkelers to go out together and do their separate activities (we dive but are traveling with family members who do not).

 

All recommendations greatly appreciated!:)