Dude... Just bring what you can bring. You'll want to enjoy your cruise, not remember how you lugged an entire camera store onto the cruise.
You can bring your entire gear, purchase every single lens at your preferred store, bring just your dSLR and your favorite lens, bring a point-and-shoot compact camera, a phone with a built-in camera... the list goes on...
So the bottom line is, know what you want to shoot, and just bring the required equipment. Want some "seascapes"? Then maybe a CPL. Just you and your family & friends having fun? Anything will do.
Which brings me to my second point. Whatever equipment you eventually choose to bring, just make the most out of it.