A cruise is organized by a specific provider, each provider has a name and a location. A cruise is identified by a number and a name and has a start and end date. A cruise requires many employees, each of whom has a name and a social security number.
Several guests take part in a cruise, each guest has a name and it is also noted whether they are a VIP or not. A guest can, of course, also take several cruises. 
The name of each ship, the number of decks, the length of the ship, and the number of passengers are known. A ship can be used for different cruises.
A cruise is booked through a travel agency. Each booking has a unique booking number and a booking date. A travel agency has a name and an address.
A cruise always heads for a specific destination area, each destination area has a name, and the name of the sea is also noted. On a cruise, guests are offered several shows, each show has a title and a certain duration.
A cruise has several guests, and each guest can participate in several cruises. Several tickets are issued for each cruise. A ticket belongs to exactly one cruise. A guest can have any number of tickets, but only one ticket per cruise.