Can my family of 5 sail in one cabin?

Each cruise line is different. The short answer to that question is:
Royal Caribbean, Norwegian, and Disney have a few cabins that will hold five – but very few. Princess, Celebrity, and Holland do not. Costa has the most cabins that can hold 5.
Carnival has many ships with cabins that hold five!
In order to get a cabin for 5 you will want to book your cruise as early as possible. Cabins for 5 and adjoining cabins are the first to sell out!