You've said exactly what others have and you're right -- 2 years old IS too young for water slides (at least where I'm from) -- even with brother's SIL having a kid to play with my kid, a cruise (outside of maybe Disney or Nickelodeon IF your kid is obsessed with a character) is out of place, imo.
Besides the fact that there isn't a lot for a child CH's age to do, who would want to PAY for that experience?
My kids BEG me to take the to Disney World & numerous other places -- besides the money factor, I tell them that the YOUNGEST has to be AT LEAST 5 or older, they have to know how to swim (for the most part), they have to know their address, phone number, parents' names, etc in case we get separated and so on... I'm always thinking worst case scenario...
Maybe I need to lighten up? But I feel my kids are not ready to get lost in the happiest place on earth -- it can happen, despite my best intentions... jmo
A cruise... UGH!!!!!!!