Maps -- The third map on this page is a road map of the Yucatan Peninsula with many highlighted points of interest.
RivieraMaya.com-- This website contains lots of information about the Mayan land and culture, as well as interesting local destinations such as eco-parks and archaeological sites on the Mayan Riviera.
Ek-Balam -- This website contains information on the ancient Mayan archaeological site of Ek Balam.
Wohlmut.com (Maya) -- This page is packed with information about touring the Yucatan Peninsula and its major Maya archaeological sites.
VisitMexico.com (Quintana Roo) -- This is the official site of the Mexican Tourism Board. Here, you can find information about the State of Quintana Roo (where Puerto Morelos is located) and things to see and do nearby.
Mexperience.com (Playa del Carmen) -- This section of Mexperience.com provides information about Playa del Carmen, which is south of Puerto Morelos on the Mayan Riviera.
Xel-Ha.com.mx (in English) -- Here you can learn about the famous eco-park Xel-Ha and plan your visit there online.
XcaretCancun.com (in English) -- XcaretCancun.com contains information about Xcaret, which is an aquatic eco-park on the Riviera.
LocoGringo (on the Ruins) -- LocoGringo.com contains lots of information about all the famous ruins you may want to visit during your stay, such as: Tulum, Coba, Ek Balam, Chichen Itza, Muyil, Chacchoben, Uxmal, and Xel-Ha.
Map Of Quintana-Roo -- Click there if you would like to see a map of the entire state of Quintana Roo, broken down into zoomable sections.

And don't forget to ask Valente for tips about the various archeological sites in the area!