There are some interesting discussions on the boards concerning passports. It is the overall consensus that everyone who is taking a cruise should have a passport. You must have one if you are traveling out of the country and doing a land vacation.
I know this is a cruise forum, I better know that
, but I see many people look at the passport as just something to be used to get on the ship.
There is no real reason to take your passport with you when you go ashore on most Caribbean islands. The chances, especially if you are fairly responsible, of not making it back to the ship are slim.
Also, if you are on a ship's tour then you are fairly well covered. The ship will "usually" wait until you return before they leave and you won't need your passport. Hopefully you won't be injured and not make it back to the ship.
The issue comes when you are on your own and going on an excursion that is going a relatively far distance from the ship. i.e. Ziplining in Puerto Vallarta where you go into the mountains away from taxi service and travel on less traveled roads, overnight in a foreign port, or a full day excursion many miles from the port. Most hotels require you to show your passport, and many will keep the passport for the duration of your stay. If you don't have your passport you will have a more complicated time getting to the next port or getting home. The photocopy of your passport photo and information pages is good but I strongly believe people put far too much stock in having this. The photocopy will not allow you to board an airplane, is not valid for ID. The main thing on that photocopy is the passport number. Having your name and passport number will shave a few hours off the time it takes to get a new passport but you are still going to have to wait at a consulate, embassy, foreign government office or hotel while the State Department issues you a temporary passport or a waiver for travel.
When you leave the ship the most important things to carry are: A government issued ID, your passport or a photocopy or passport number and the name, address and phone number of the ship's agent. I can't stress the importance of having the ship's agent's contact information. This is the person to call if you miss the ship. This information is in the daily newsletter for each port you visit. Tear or cut it out and take ashore with you.
If I am doing land travel in a foreign country I rarely carry my passport when sightseeing. I don't use traveler's checks and my hotel or wherever I'm staying isn't going to leave at 5:00 p.m.. On a cruise it's a different story. I do most of my excursions on my own and often there is a chance something could happen such as a mechanical breakdown or some driver gets lost and I may not make it back to the ship. Then I carry the passport. I keep it as secure as possible.
So: If you are going out on your own think about the possibilities of not making it back to the ship and weigh the odds. If in doubt take the passport. It's purpose is more than just getting on the ship.