i am used to traveling in more third world countries on low budget trips. i liek to adventure and check out cool views sports activities, hikes anything kinda non "tourist" i am landing in cancun and i have 3 weeks. does anybody have suggestions of what to do. thanks

I would get a guide book and read it.

i was looking for ideas... is there any well known dive sites?

There are great excursions to cenotes for cave diving in Yucatan. You can read our article here: http://www.yucatantoday.com/destinations/eng-cenotes.htm

Interested in low-budget travel in non-tourist places? Then you will need to flee Cancun as you would the plague.

Go directly from the Cancun airport to the bus station, buy a ticket to Valladolid or Merida and escape. Bus your way down to Palenque in Chiapas or along the Gulf coast through Campeche.