The number one reason people book a cruise is for the destinations Royal Caribbean ships visit, but you may want to know if you have to book an excursion on a cruise.

I love to explore the ports of call my ship visits because of how much there is to see and do. Experiencing new cultures, visiting historical sites, and forgetting all my cares at the beach are things I look forward to on every sailing.
The conundrum is often not what to do, but how to book it. Is it better to book shore excursions with the cruise line? Or can you do your own excursions on a cruise?
Here are the basic things to consider before you book cruise shore excursions so that you can make the right decision.
What are the pros and cons of booking excursions through the cruise line?

You can book shore excursions through Royal Caribbean, and it's clearly the easiest option.
As soon as you book a cruise, you're able to access the Cruise Planner and see the variety of tours sold. The cruise line has gone through and vetted tours and present ones that you can book quickly.
That's the best thing about cruise line excursions: they're simple, easy to book, and come with a few guarantees.

First, it's a tour operator that is reputable. That means each excursion has to pass an inspection by the cruise line and it's a company that knows what it's doing.
An equally important promise is that you won't miss the cruise ship.
One of the most important rules on any cruise is to be back onboard before all-aboard time, or you'll be left behind.

Royal Caribbean says if you book a tour with them, they'll get you back on the ship. In most cases, this means if the tour is running behind schedule, the tour operator will contact the ship and inform them so the ship can wait.
This is especially important when taking a tour that requires long transportation time back to the ship, such as a nearly 3 hour bus ride to Paris from Le Havre, France.
The disadvantages of booking a cruise line excursion is it's not going to be the cheapest option.

Many veteran cruisers lament the generally higher prices for cruise line excursions.
Royal Caribbean works with high quality tour operators, and of course they make a commission on the sales too. Objectively, a cruise line excursion will usually cost more.
Another issue is that cruise excursions tend to sell out quickly.

Royal Caribbean has been particularly successful in marketing its app to cruisers, and the result is a higher visibility to book tours.
Decades ago, you could wait until you got on your ship to book tours. Now, that's practically a mistake because there will be so few options left.
Another problem I have with cruise tours are they tend to include large groups.

Large groups move slowly, require more stops, and it seems to me to have a lot of wasted time.
Royal Caribbean recently introduced Royal Signature Excursions, that feature smaller groups and even skip-the-line options. Of course, don't expect these to be inexpensive.
Shore excursions are not cheaper on ship

Don't purposefully wait to book a shore excursion until you're on the ship because you're expecting a last-minute deal.
Royal Caribbean actually charges the most onboard. Think of it like paying the rack rate at a hotel when you walk up, instead of pre-booking online.
There are sales every few weeks on excursions, and the pre-cruise price is almost always cheapest.
For example, I've seen Royal Caribbean advertise up to 30% off excursions booked before the sailing.
Is it safe to book independent cruise excursions?

The short answer is yes, but you need to do your research.
Independent shore excursions offer a much greater variety of tours and at different price points. You can find budget friendly ones, or a lavish all inclusive option.
The important thing is to look up reviews of the tour operator and the specific tour you're considering before booking.

The onus falls on you to vet the tour, rather than the cruise line.
New cruisers may find this to be a daunting task, filled with hesitation regarding making a mistake. In that case, there's nothing wrong with sticking to ship tours.
The primary risks are time and the tour delivering on what you expect.

Certainly, you'll want to get back to the ship on time. No tour operator wants you to miss the ship, because that kind of bad review is bad for business.
I recommend planning to get back at least 2 hours prior to the all aboard time, so that an unexpected problem (i.e traffic, a medical emergency) doesn't hinder your ability to get back.
Most cruise experts point out that independent tours can save you a lot of money. Plus, if the cruise line doesn't offer the activity you like, you can find one that does with your own company.

Before you book , be sure to also look at the cancellation policy.
Royal Caribbean will refund your money if the ship is unable to dock at a port because of weather or an itinerary change. Some independent tours may keep your deposit or not offer refunds if you can't make it.
Independent tours don't always offer full refunds if there's an itinerary change, but ship tours always do.