Generally, the casino is open whenever the ship is in international waters. So, yes, it will be open on the sea days. It can also be open in between the ports in Hawaii if they take the ship out far enough from shore.
Rick's information is the best here. I wouldn't plan on the casino being open while in the islands, although it could happen. And this is not something that varies between the cruise lines. They usually have to abide by special rules when in Hawaii, and also in Alaska.
The casino will be closed when cruising the islands. We were told, when onboard Regal, that this is Hawaiian law, and it is a definite that they will be closed. They will be open during the four days to Hawaii and the four or five days on the way home. (If you are losing, you will be glad of the forced break LOL).
Thanks for the update, Ellie. I am not a big gambler so I rarely keep track of the casino hours. I'll spend $100 and maybe an hour at the slots on a typical cruise. It just doesn't interest me that much.
Thanks Ellie, hopefully there will be enough activities to keep my attention wether I can just watch or maybe do some activities to keep me from losing to much in there casino, lol. I can't do alot in the wheelchair but I am sure I will enjoy watching many do activities and I know I will enjoy the shows and I saw they have things where you can take classes for computers and paint ceramics so I shouldn't have to spend to much time in the casino but I do like slots but not if I am going to lose to much. Shana