Under UK GDPR the lawful basis matters, so here it is in one line: this site processes no personal data of its own. It keeps no accounts, sends no newsletter, runs no contact form and asks for nothing about you at any point.
Cookies are a separate question, and PECR is what governs them. Non-essential cookies — the advertising ones — are set only after you agree through the notice that appears on your first visit. Decline, and they are not set. Change your mind later and the same notice can be reopened.
The adverts themselves come from Google AdSense. Google and the vendors it works with act as their own controllers for that processing: they decide what to collect and why, and their policies rather than this page describe it. Nothing about your visit is passed from here to any ferry operator or tourist board.
Readership is counted in the aggregate, to work out which crossings are worth researching next. There is no profiling and nothing is sold.
If something here concerns you, write to [email protected]. You also have the right to complain to the Information Commissioner's Office, which supervises this area in the UK.