While it is not easy to get a free cruise, it is certainly possible. Outlining two possible methods that you could use.
Is it possible to get a free cruise? Of course it is. It is not easy or even likely but it is possible.
First there are mystery shoppers. Mystery shopping is a way for companies such as retailers to get into their stores and see what is going on from a customer’s perspective without any of the staff realizing it. The shopper has a pre-determined list of things to look at and make mental notes of, such as the presentation of the product, the conduct and friendliness of the staff and possibly many other criteria. A mystery shopper is required to have a keen eye for detail, as sharp memory and write excellent reports.
You will start with simple shops such as CD stores, book stores, pizza places and other simple eating and shopping establishments. Gradually, a good shopper will work their way up to better eating establishments and possibly jewelry and movie theatres. Some but not all mystery shopping companies will also do Cruises and other vacation spots.
A free cruise earned in this way is not to be considered a vacation. While you are permitted and even encouraged to enjoy all the amenities and luxuries on board ship, your primary function is to review the shipboard operations, while maintaining your anonymity throughout the cruise.
The other possible way of earning a free cruise is to act as an onboard lecturer. This is equally complicated but could possibly earn you two or three free cruises a year as you gain experience and expertise.
If you can convince a cruise line that you are an expert in a field that might interest cruise passengers then they will provide you with basic accommodations and food and most of the shipboard amenities in exchange for one lecture every sea day. A sea day is any day that the ship does not visit a port of call.
As a result, you would be free to visit any port of call that you wish, just like any other passenger. It would require some legwork to initially convince a cruise line that you qualify as an expert in a given field but it would be worth the effort in the long run since your experience the first time would serve you if you wanted to try it again.