I am an Indian Passport holder living in the US (H1B multiple entry
work visa) who is planning on taking a cruise with another traveller
(Indian passport holder, multiple entry US visitor visa).
The ship (Royal Caribbean Monarch of the Seas) leaves from Los Angles
and touches a Mexican port for less than 24 hours (schedule as below)

DAY  DATE  PORT  ARRIVE    DEPART  
Fri Dec 22 Los Angeles, CA   5:30pm 
Sat Dec 23 Catalina Island, CA  8:00am 5:00pm 
Sun Dec 24 San Diego, CA  7:00am 5:00pm 
Mon Dec 25 At Sea   
Tue Dec 26 Ensenada, Mexico  8:00am 5:00pm 
Wed Dec 27 Los Angeles, CA  7:00am 

The Question is this:
Will my travelling companion and I (both Indian passport holders)
require some kind of Mexican visa or Mexican paperwork in order to
board the ship?

I need an answer within the next week or so. (today is 11/17/2006)

Good news! According to the Mexican Embassy for India, you do not need
to get permission in advance.

This information is in two places on the Embassy's web site, once in
English and once in Spanish. The Spanish version has a bit more
information, so I'll provide a translation for you.

First the English version:

Embassy of Mexico in India: Leisure Cruises
http://portal.sre.gob.mx/indiaeng/index.php?option=displaypage&Itemid=58&op=page&SubMenu=
Regardless of their nationality, foreigners traveling on leisure
cruises, who have embarked the ship in a third country, do not require
visa or Entry Permits' to visit Mexican seaports. Their arrival will
be authorized by the National Institute of Migration directly at the
port.

Now in Spanish:

Embajada de México en India
http://portal.sre.gob.mx/india/index.php?option=displaypage&Itemid=91&op=page&SubMenu=
4. Viajaré en crucero a México, ¿qué debo hacer?
Si usted aborda la embarcación en otro país y sólo visita puertos
mexicanos por menos de 24 hrs, no es necesario obtener una visa de
turista. Las autoridades del barco harán los trámites necesarios ante
las autoridades mexicanas y le darán toda la información pertinente
para que pueda desembarcar por unas horas.

My translation:

4. I will travel by cruise to Mexico. What should I do?
If you get on board in another country and only visit Mexican ports
for less than 24 hours, it isn't necessary to get a tourist visa. The
boat authorities will do the necessary paperwork in the presence of
the Mexican authorities and will give you all the pertinent
information so that you can get off the boat for a few hours.

Similar information is on Mexican consular page for other countries as well:

Bienvenidos a la Sección Migratoria
http://www.sre.gob.mx/ecuador/portalweb/consular/sermigra/migraresum.htm
PASAJEROS EN CRUCEROS
Los extranjeros que pretendan visitar puertos marítimos mexicanos como
pasajeros en cruceros turísticos no requieren visa ni permiso previo
en la representación consular, independientemente de la nacionalidad.
El desembarco en el puerto de entrada será autorizado en los términos
que determine el Instituto Nacional de Migración.

My translation:

CRUISE PASSENGERS
Foreigners who plan to visit Mexican seaports as passengers on tourist
cruises do not need a tourist visit nor advance permission from a
consular representative, regardless of nationality. Disembarking in
the entry port will be authorized in terminals designated by the
National Immigration Institute.

IMPORTANT NOTE: As indicated above, the Mexican government will not
bar you from setting foot in the country. However, you still need to
make arrangements with Royal Caribbean in advance so their folks can
make the necessary arrangements.  Even if you weren't going to Mexico,
you would want to check with Royal Caribbean to make certain you have
the paperwork with you necessary to return back to the United States
once you are through with your cruise.

You can contact Royal Caribbean here:

Royal Caribbean International - Royal Caribbean Customer Support
http://www.royalcaribbean.com/customersupport.do

I visited Ensenada a few years ago (although I traveled there by land)
and found it an interesting city to visit. I hope you enjoy it.

Have a great trip,

Mvguy-ga







Google searches used:

"mexican embassy" india
://www.google.com/search?q=%22mexican+embassy%22+india

site:gob.mx crucero migración pasaporte
://www.google.com/search?q=site%3Agob.mx+crucero+migraci%C3%B3n+pasaporte

I suggest that you contact the line and ask your question:
http://www.royalcaribbean.com/customersupport/home.do;jsessionid=0000bTHSev8r_Pt6evqOYMAm4do:10ktmeta1?cS=NAVBAR

or here and click on Customer Support:
http://www.royalcaribbean.com/findacruise/ships/class/ship/home.do?br=R&shipCode=MN

Cruise passengers are often issued an ID card that is used for on
board charges and identification when going ashore and returning,
which also serves as identification at customs.  This MAY obviate the
necessity for a visa for daytrips.

Royal Caribbean should know.

Whatever, have a great cruise!

From my one experience of a cruise that stopped in a variety of
countries, at the beginning of the voyage they grabbed our passports
and gave us plastic swipe cards (no photos).

At the end of the voyage, they generously returned our passports.

Immigration were singularly uninterested in us.

As MyOarin advized, contact the cruise company.