These are all of the things I wanted when I was on my last cruise. You can decide what will help you on your next cruise.
Offline map of your ports will be helpful when you are walking around.
Offline TV Shows and Movies for passing time while over the ocean. Netflix and Amazon Video both offer this.
Blu-Ray or DVD player with HDMI to hook up to your state room TV.
Offline music for dancing in your state room.
Audiobook or podcasts for listening and learning.
No network required cell phone games.
Better state room
Fan to keep cool.
Bluetooth speaker to dance to loud music instead of a cell phone speaker.
Old hotel key or credit card to keep the lights and AC on when you are out of the room.
Hot water kettle for hot water or tea.
Wine bottle opener for opening wine, but they will provide a cheap one if you ask.
FireChat (android) (iOS) is an app that works over Bluetooth and Wi-Fi, but no Internet connection is required. The more people that use it, the larger its network gets.
Walkie talkies for talking with each other but probably only useful on the smaller ships.
International phone (or T-Mobile for data) so you can call home or local businesses at port.
Fun and Games
Balance app on phone to see how much the boat is rocking.
Binoculars to look out your window at stars, the moon, and other ships.
Poloraid camera so you can capture the memories and enjoy them privately and immediately.
Hand sanitizer because everything could be dirty.
Spray sunscreen so you can quickly apply when you are on the deck or out at shore. Better than wasting time with the lotion sunscreen.
Extra clothes for changing a lot because there is a lot of fun in dressing up and getting out of sweaty clothes.
Gatorade power mix so you don’t have to drink just water and lemonade (no alcohol and soda plan).
A money clip, see through phone case, or credit card pocket for phone because you only need to carry around your phone and room key while on the ship.