It CAN be hit or miss unless you do some research before hand. I've had pretty good experiences booking dives through the cruise line. Then again, I've NEVER paid $100 or even seen one priced high unless that price included full rental gear.
As far as profit margins, I had a dive cancelled on a stop in Cayman. The cruise line was going to charge me $85. I found Don Fosters and paid $75. The cruise also had ground transportation arranged to Red Sail so I thought they were NOT ripping anyone off (mind you they likely don't pay retail to the local operators).
If you book your own dives and run late, the ship WILL leave you. If the dive was booked through the cruise line, the ship will wait
As far as profit margins, I had a dive cancelled on a stop in Cayman. The cruise line was going to charge me $85. I found Don Fosters and paid $75. The cruise also had ground transportation arranged to Red Sail so I thought they were NOT ripping anyone off (mind you they likely don't pay retail to the local operators).
If you book your own dives and run late, the ship WILL leave you. If the dive was booked through the cruise line, the ship will wait