A cruise ship is a really big boat that floats on the water. You can think of it like a floating city because it has everything you might find in a city! Just like in a city, cruise ships have decks, which are like streets where people can walk around and see the beautiful ocean.
On the decks, you might see people relaxing by the pool, eating yummy food, or playing games. There are also fun activities, just like going to a park! So, when you're on a cruise ship, it feels like you are taking a little vacation in a special city that floats on the sea!