Identify a complementary good or service industry connected with cruise ships?

There are many complementary goods or services to a cruse ships. Some cruise operators go very far in developing new entertainment concepts on board of their vessels, including surf pools, planetariums, on-deck LED movie screens, Golf simulators, water parks, demonstration kitchens, multi-room villas with private pools and in-suite Jacuzzis, ice-skating rinks, rock-climbing walls, bungee trampolines and other. Onboard services account between 20 and 30% of the total cruise line revenues.