On a cruise ship, the person in charge is called the captain. The captain is like a big boss who makes sure everyone is safe and happy. Just like how your teacher helps you in class, the captain helps the crew and all the people on the ship.
There are also other important people, like the first officer, who helps the captain, and the crew, who do different jobs like cooking and cleaning.
So, think of the captain as the leader of a fun team on a big floating house that sails on the water!