This is the website idea for a niche market. You can create a website focussing solely on cruises by destination and thereby target the affluent group of people who are interested in this luxury travel experience.
Provide information about specific destinations and cruise options and allow customers to easily find and compare the best options for their needs.
A blog dedicated to cruises by destination will make it easier for search engines to categorize your content and rank better in search results.
You can then consider tying up with booking agencies by establishing yourself as an authority in the industry.