For beginning cruisers, here's a primer on the essentials:
passports, transfers, cruise tickets and what's included in a cruise

So you've decided to take a cruise, but you are unsure about the
process: What's included in your cruise reservations, and what are you
required to know, bring and do in order to fulfill your cruise
reservation obligations?

Cruise Reservation Basics

Before you select a ship and itinerary, make sure you have the proper documents to travel overseas.

Because almost all cruises will sail to a foreign port, you will
need a passport or equivalent documentation to prove you are an
American (or other) citizen. Leaving your country of origin isn't the
problem -- it's getting back in when you return. So if you don't have
the proper documentation, you will not be allowed to board the ship at
the beginning of the cruise. The same cruise ship will be bringing you
home, and it is their job to make sure you are qualified to re-enter
the country.

Passport Requirements for Cruise Reservations

Cruise lines will take a reservation even if you do not currently
have the proper documentation, but they will warn you of the need to
get it before you attempt to board the ship. The best proof of
citizenship for traveling worldwide by ship, air or even by foot is the
good old passport. However, a passport is not required for many cruises
originating in the United States.

Due to federal laws requiring most cruise ships to stop in at least
one foreign port, you will need proof of citizenship to board the
cruise ship. However, a new law called the Western Hemisphere Travel
Initiative (WHTI) says that U.S. citizens who cruise to Mexico, Canada
or the Caribbean Islands can cross U.S. borders as long as they have a
certified birth certificate and a state-issued picture ID, such as a
driver's license.

This exception can save cruisers a lot of money, since passports
generally cost more than $100 per person these days. However, there are
a few caveats. WHTI only applies to people arriving in the U.S. by sea
or land crossings. Arriving by air still requires a valid passport.
This is usually not an issue for cruisers, but if there is an emergency
and you need to fly home during your cruise, you have to go to a U.S.
embassy and get a temporary passport. (Exception: children under 16 are
allowed to travel with a certified birth certificate and state-issued
picture ID at any time.)

A birth certificate is considered certified if it is issued by the
clerk of the court for the county in which you were born, and it has a
raised seal. No other birth certificate is accepted, including the
hospital certificate with the picture of your footprints.

There are other alternatives to passports. Since 2008, the U.S.
government has issued something called the Passport Card, available to
people who want to travel overseas by sea or land borders, but not air.
A few states (Washington) now issue Enhanced Driver's Licenses that
also serve as proof of U.S. citizenship. These are accepted at any U.S.
border despite the state of issuance. But you still need a passport if
you have an emergency and want to return to the U.S. by air.

Cruise Reservation Documents

Once you have covered your passport requirements, you are ready to
book your cruise. When you do, you will receive your cruise ticket.
This is usually sent to you by mail or package delivery from your
travel agent. Most of the time, you get a lovely booklet containing
your cruise ticket, a brochure of shore excursions, descriptions of the
ship, and luggage tags to put on your bags so they can be delivered to
your stateroom.

If you want, you can purchase pre-paid transfers from the airport to
the ship. If you do, transfer vouchers will be included with your
cruise documents. Keep them handy so you can use them at the airport. A
cruise line representative will meet you in the baggage claim area of
the airport and take your transfer tickets. Once you receive your bags,
put the cruise line's luggage tags on them and get on the provided bus
to take you directly to the ship. The other option, which is often
cheaper, is to take a taxi directly to the ship.

Once you arrive at the ship you should have your cruise luggage tags
on your bags before you turn them over to the stevedore. This is the
person who will deliver the bags to the ship, but he will not take them
aboard and drop then at your cabin door. The ship's crew, specifically
the room stewards, do that. (So do not feel compelled to over-tip the
stevedores. They will say they are responsible for getting your bags to
your cabin, but it isn't true.)

Only give the stevedores the bags you will not need for the next
several hours. Keep your passports, cruise documents, valuables and
medication in your carry-on bags to board the ship. You will need your
documentation to board.

After you pass through security, you will check in for boarding. The
agent will issue you keycards, which you need to get onboard. As you
enter the ship, they will snap a picture of you that goes into your
keycard (but only in digital form, you cannot see it). You will use
your keycard for purchases on the ship, to get in and out of your room,
and to get on and off the ship in port. Some lines call it a sign
& sail card.

Be sure to keep your keycard until you leave the ship (you can't get
off the ship without your card, because they need to be sure you paid
your final bill). Once you disembark the ship for the last time, they
will give you back your card and you can keep it as a souvenir.

After you leave the ship, you will need to go through federal
customs and immigration. This is the point where you really need a
passport or equivalent documentation. You will also receive a customs
card to fill out and show to officials, documenting what you bought
during your trip and are bringing back into the U.S. The limit you can
spend without paying duty is $800 per family. Beyond that, you must pay
duty equal to about 16 percent of the value of your purchases. Certain
items like alcohol and tobacco have other limits you should research
before you buy. Each duty form applies to one family, not per person.

Summing Up Cruise Reservations

That is the long and short of a cruise reservation. Always make a
checklist of the documentation you will need, and verify it long before
you leave for your trip. Keep your documents in a safe place in your
carry-on bags at all times. You never want to be separated from your
official identification.