All About Cancún: www.cancunmx.com
This site is a good place to start planning. Their database, called "The Online Experts," answers many of the most common questions. It's slow but current, with input from lots of recent travelers to the region.
Cancún Convention & Visitors Bureau: www.cancun.travel
The official site of the Cancún Convention & Visitors Bureau lists excellent information on events and attractions. Its hotel guide is one of the most complete available and includes events and news related to Cancún.
Cancún Online: www.cancun.com
This comprehensive guide has lots of information about things to do and see in and around Cancún, though most details come from paying advertisers. The site lets you reserve package trips, accommodations, activities, and tours.
Cancún Tips: www.cancuntips.com.mx
The online version of the free tourist guide, it's most useful for its maps, images, and other trip-planning tools.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.