Who can leave a review?
Only guests who actually took the trip. A review can only be written against a booking that has been marked completed, so nothing on this site comes from someone who never sailed.
Reviews are tied to bookings in the database. No booking, no review — which means a captain cannot post about themselves, a rival cannot post about them, and nobody can review a trip they only thought about taking.
It is a smaller number of reviews than a site with open submissions would show. It is also worth more when you are deciding who to trust with a day of your holiday.