As a way to boost demand for a sailing, cruise lines may periodically offer 2 for 1 cruise rate promotions, providing significant value for guests. If this promotion is available on the website, it will display the reduced price, which is divided by two.
Generally means that two people can share a cabin or stateroom for the price of one person. In other words, it is a discounted rate where the second person's fare is significantly reduced or even free.
MSC often offers this promotion for its Caribbean products.