Hi Christie,
I was certified, twice, on RC ships, with three attempts (due to getting sick) as SCUBA diver and upgrade to Open Water. The only items necessary are mask and snorkel. If you have picky feet, like me, I would also buy fins in advance, but it is not necessary. The cost of the course includes all other gear. I have attached the SCUBA course outline I received October 2017, as I cannot find a later copy. The number of stops on the cruise will determine the exact days of pool sessions and open water sessions.
I hope this helps, if you have any questions, don't hesitate to ask
HM Scuba Course Schedule LB, FL, CZ no cw on D6.pptx