Depending on the ship you will have Wi-Fi in the cabin or certain public areas or both. None of it is free even with your own laptop. There are different pkgs of minutes available but it is not cheap.
50 Carnival: Mardi Gras, Ecstasy X2, Fascination X6, Celebration, Elation X5, Glory X4, Fantasy X4, Valor, Holiday X3, Imagination, Liberty, Spirit X2, Freedom, Destiny X2, Splendor X2, Dream X2, Conquest, Legend X2, Victory, Sensation, Paradise, Inspiration, Magic X2, Triumph, Miracle, Breeze
5 Norwegian: Sky, Jewel, Dawn, Epic, Pearl
6 Windjammer: S/V Legacy X3, S/V Polynesia, S/V Caledonia, S/V Diamant