I prefer to pay on board, if I book a ships excursion, but that is rare...You will get a credit if you choose to cancel within the expressed time frame,or if, for whatever reason, the ship may cancel it. Prepaying does assure you of your place though, especially if it may be a coveted excursion...
Trip, with her book & tea!
Chat Hostess & Board Moderator
On most ships, shore excursions are charged to your shipboard account, whether they are pre-booked or booked onboard. So you pay for them in either case at the end of the cruise.
The exception we have encountered is HAL which charges your excursions to your credit card when they are booked. They are, however, fully cancellable under the same terms as bookings aboard.
In general, we book well in advance on excursions that we REALLY want to go on, and especially things like helicopters or cruise boats that can fill up quickly. If there are excursions we are undecided on or those that will usually have plenty of space, like city tours or beach resorts, we may wait til we are aboard.