The Royal Caribbean International cruise line announced it will launch a new bid-based stateroom upgrade program on November 28, dubbed RoyalUp.

According to the unofficial Royal Caribbean blog, passengers will receive an email from the cruise line if they are booked on a RoyalUp eligible voyage and have the opportunity to browse through staterooms available for upgrade.

Customers will select the price they would be willing to pay for the upgrade and bid against other passengers on the sailing. The offers from passengers are per person for the entire duration of the cruise and based on two occupants per stateroom.

For parties of more than two, only the first and second guest on the reservation will pay the amount offered. Passengers do not get to pick the location or specific features of the upgraded cabin, and Royal Caribbean can’t guarantee groups are upgraded together.

Customers who booked their voyage with a travel agent can let them handle the entire bidding process, and guests are permitted to make bids across multiple categories to increase the chances of getting an upgrade.

The upgrades can be accepted at any time, but passengers can modify or cancel the offer up until two days prior to departure. The changes can only be made if Royal Caribbean has not accepted the offer.