Book independently if you can!!!! We actually did our first couple trips to Coz on cruise ships. Since Coz is a relatively small island, it's not a big problem to book independent and get back to your ship with plenty of time. Although you may have to shop around a bit to find an op to fit your schedule... depending on what time the ship docks. And as time gets closer, you may have availability problems, as the good ops get booked up!! Like cv, we use Scuba with Alison. We stumbled across her 7+ years ago while looking for an op to use on a cruise ship stop. Alison was great, and actually was able to adjust her schedule a bit to accommodate us. It was a matter of jump ship, grab a cab to the marina, fill out a bit of paperwork and have FUN!! After that we booked with her on any Coz cruise stops, then eventually just started flying in to spend a week or more diving with her. (We're spending 9 days with her in March!) I'm sure some others will chime in with recommendations, and the best I could suggest is shoot off e-mails asap to those that interest you to see who has space for you, and times that work.